Interview Questions

SQL Server T-SQL Interview Questions

Question : What are the two commands to remove all of the data from a table? Are there any implications with the specific commands?
The DELETE command.
The TRUNCATE command.
In terms of implications, a few different issues could occur:
With the DELETE or TRUNCATE command, you will lose all of your data in a table.
A single DELETE command could fill up the transaction log since it is a single transaction.
A TRUNCATE command could cause issues for Log Shipping since it is a minimally logged operation.

Question: What are the three ways that Dynamic SQL can be issued?
Writing a query with parameters.
Using EXEC.
Using sp_executesql

Question: True or False – SQL Server can format the date in over 10 different patterns.
True – With the CONVERT command there are over 15 different date formats such as MM/DD/YY, MM DD, YY, DD-MM-YY, etc.

2. How do we handle Error?
Ans: I think we can use @@Error. Right after the query condition is executed we can check for @@Error <> 0, if it is not returning zero mean some error occured. Raiserror is another command for raising error We can also use Try catch block

What is PatIndex?
Ans: Returns the starting position of the first occurrence of a pattern in a specified expression, or zeros if the pattern is not found
Syntax – PATINDEX ( ‘%pattern%’ , expression )

SELECT PATINDEX(‘%ensure%’, Character_Column_For_Search)
FROM Table_Name

How to query a string contains %?
Ans: SELECT Name FROM tblPlayer WHERE Name Like ‘%[”%”]’

How to get values from a table with comma seperated?
Ans: declare @vName nvarchar(100)
set @vName = ”
select @vName = @vName + ‘,’+ [Name] from HumanResources.Shift
select @vName

How to update ‘Yes’ to ‘No’ and viceversa in a query?
Ans: Update tablename set ColumnName1 = (case ColumnName1 when ‘Yes’
then ‘No’else ‘Yes’ end)

Consider you have a table with columns ID(primary key), Country and State.
Now if you have some rows with combination of country and state repeating,
ie, two rows with combination India, Kerala. Write a query for deleting
duplicate records?

Ans: With T1 as
(Select *,Row_Number() over (partition by Country, State order by ID)
as ‘RowNo’ From TableName)
Delete from T1 where RowNo > 1;

How to create temporary table? How do we apply noncluster index? What is nolock? When and where is nolock applied normally?

Ans. Two ways of creating temporary table with non clusterindex applied on it. Also example shows how to apply “nolock”. nolock is normally applied while querying on production servers. This would make the records being queried sharable on the table. ie, will not prevent other queries from querying the same record parallely on same table. The risk will be nolock might return junk data some times because the select query might be querying the table while some other insertion or updation commands are performed on the table.

OfficeName varchar(50)
, officeid int
, CustID int
, AgentID int
, mlsid varchar(4)
, RequestMoreDetails int null
, Emails int null

, officeid
, o.CustID
, AgentID –
, o.mlsid
, PrintBrochure_Views = null
, RequestMoreDetails = null
, Emails = null
into #ForOffices from #Offices o
LEFT JOIN dbo.planparts WITH (NOLOCK)
ON bppa.officeid = o.RID

Difference between stored procedure and function

1) Procedure can return zero or n values whereas function can return one value which is mandatory.
2) Procedures can have input, output parameters for it whereas functions can have only input parameters.
3) Procedure allows select as well as DML statement in it whereas function allows only select statement in it.
4) Functions can be called from procedure whereas procedures cannot be called from function.
5) Exception can be handled by try-catch block in a procedure whereas try-catch block cannot be used in a function.
6) We can go for transaction management in procedure whereas we can’t go in function.
7) Procedures cannot be utilized in a select statement whereas function can be embedded in a select statement.

CAST versus CONVERT in SQL Server

1. CONVERT is SQL speicific but CAST is ANSI standarised
2. CONVERT deal nicely with datetime using format, which is missing from CAST

Q. What is the maximum limit of SQL Server instances for a standalone computer?
· 50 instances on a stand-alone server for all SQL Server editions. SQL Server supports 25 instances on a failover cluster.

Q. Can we install SQL Server using a configure file?
Yes! We can prepare a configuration file. While installing SQL Server the path to the configuration file is specified in the “Ready to Install” page in the configuration file path section. Cancel the setup without actually completing the installation, to generate the INI file.
File Location and Name:
%programfiles%\Microsoft SQL Server\110\Setup Bootstrap\Log\\ConfigurationFile.ini.

Q. What are the top performance counters to be monitor in Performance Monitor?
Processor\%Processor Time: Monitoring CPU consumption allows you to check for a bottleneck on the server (indicated by high sustained usage).
High percentage of Signal Wait: Signal wait is the time a worker spends waiting for CPU time after it has finished waiting on something else (such as a lock, a latch or some other wait). Time spent waiting on the CPU is indicative of a CPU bottleneck. Signal wait can be found by executing DBCC SQLPERF (waitstats) on SQL Server 2000 or by querying sys.dm_os_wait_stats on SQL Server 2005.
Physical Disk\Avg. Disk Queue Length: Check for disk bottlenecks: if the value exceeds 2 then it is likely that a disk bottleneck exists.
MSSQL$Instance: Buffer Manager\Page Life Expectancy: Page Life Expectancy is the number of seconds a page stays in the buffer cache. A low number indicates that pages are being evicted without spending much time in the cache, which reduces the effectiveness of the cache.
MSSQL$Instance: Plan Cache\Cache Hit Ratio: A low Plan Cache hit ratio means that plans are not being reused.
MSSQL$Instance:General Statistics\Processes Blocked: Long blocks indicate contention for resources.

sql> SELECT * FROM runners;
| id | name |
| 1 | John Doe |
| 2 | Jane Doe |
| 3 | Alice Jones |
| 4 | Bobby Louis |
| 5 | Lisa Romero |

sql> SELECT * FROM races;
| id | event | winner_id |
| 1 | 100 meter dash | 2 |
| 2 | 500 meter dash | 3 |
| 3 | cross-country | 2 |
| 4 | triathalon | NULL |
What will be the result of the query below?
SELECT * FROM runners WHERE id NOT IN (SELECT winner_id FROM races)

CREATE TABLE dbo.envelope(id int, user_id int);
CREATE TABLE int, pageseq int, doctext varchar(100));



What will the result be from the following query:
UPDATE docs SET doctext=pageseq FROM docs INNER JOIN envelope ON

What is wrong with this SQL query? Correct it so it executes properly.
SELECT Id, YEAR(BillingDate) AS BillingYear
FROM Invoices
WHERE BillingYear >= 2010;

Given these contents of the Customers table:
Id Name ReferredBy
1 John Doe NULL
2 Jane Smith NULL
3 Anne Jenkins 2
4 Eric Branford NULL
5 Pat Richards 1
6 Alice Barnes 2
Here is a query written to return the list of customers not referred by Jane Smith:
SELECT Name FROM Customers WHERE ReferredBy <> 2;
What will be the result of the query? Why? What would be a better way to write it?

SELECT * FROM users;

user_id username
1 John Doe
2 Jane Don
3 Alice Jones
4 Lisa Romero

SELECT * FROM training_details;

user_training_id user_id training_id training_date
1 1 1 “2015-08-02”
2 2 1 “2015-08-03”
3 3 2 “2015-08-02”
4 4 2 “2015-08-04”
5 2 2 “2015-08-03”
6 1 1 “2015-08-02”
7 3 2 “2015-08-04”
8 4 3 “2015-08-03”
9 1 4 “2015-08-03”
10 3 1 “2015-08-02”
11 4 2 “2015-08-04”
12 3 2 “2015-08-02”
13 1 1 “2015-08-02”
14 4 3 “2015-08-03”

count( user_training_id ) AS count
FROM users u JOIN training_details t ON t.user_id = u.user_id
GROUP BY user_id,
HAVING count( user_training_id ) > 1
ORDER BY training_date DESC;
user_id username training_id training_date count
4 Lisa Romero 2 August, 04 2015 00:00:00 2
4 Lisa Romero 3 August, 03 2015 00:00:00 2
1 John Doe 1 August, 02 2015 00:00:00 3
3 Alice Jones 2 August, 02 2015 00:00:00 2

What is an execution plan? When would you use it? How would you view the execution plan?

An execution plan is basically a road map that graphically or textually shows the data retrieval methods chosen by the SQL server’s query optimizer for a stored procedure or ad hoc query. Execution plans are very useful for helping a developer understand and analyze the performance characteristics of a query or stored procedure, since the plan is used to execute the query or stored procedure.
In many SQL systems, a textual execution plan can be obtained using a keyword such as EXPLAIN, and visual representations can often be obtained as well. In Microsoft SQL Server, the Query Analyzer has an option called “Show Execution Plan” (located on the Query drop down menu). If this option is turned on, it will display query execution plans in a separate window when a query is run.

Microsoft SQL Server   Interview Questions (FAQs)

Use views and stored procedures instead of heavy-duty queries.

This can reduce network traffic, because your client will send to server only stored procedure or view name (perhaps with some parameters) instead of large heavy-duty queries text. This can be used to facilitate permission management also, because you can restrict user access to table columns they should not see.

  • Try to use constraints instead of triggers, whenever possible.

Constraints are much more efficient than triggers and can boost performance. So, you should use constraints instead of triggers, whenever possible.

  • Use table variables instead of temporary tables.

Table variables require less locking and logging resources than temporary tables, so table variables should be used whenever possible. The table variables are available in SQL Server 2000 only.

  • Try to use UNION ALL statement instead of UNION, whenever possible.

The UNION ALL statement is much faster than UNION, because UNION ALL statement does not look for duplicate rows, and UNION statement does look for duplicate rows, whether or not they exist.

  • Try to avoid using the DISTINCT clause, whenever possible.

Because using the DISTINCT clause will result in some performance degradation, you should use this clause only when it is necessary.

  • Try to avoid using SQL Server cursors, whenever possible.

SQL Server cursors can result in some performance degradation in comparison with select statements. Try to use correlated sub-query or derived tables, if you need to perform row-by-row operations.

  • Try to avoid the HAVING clause, whenever possible.

The HAVING clause is used to restrict the result set returned by the GROUP BY clause. When you use GROUP BY with the HAVING clause, the GROUP BY clause divides the rows into sets of grouped rows and aggregates their values, and then the HAVING clause eliminates undesired aggregated groups. In many cases, you can write your select statement so, that it will contain only WHERE and GROUP BY clauses without HAVING clause. This can improve the performance of your query.

  • If you need to return the total table’s row count, you can use alternative way instead of SELECT COUNT (*) statement.

Because SELECT COUNT (*) statement makes a full table scan to return the total table’s row count, it can take very many time for the large table. There is another way to determine the total row count in a table. You can use sysindexes system table, in this case. There is ROWS column in the sysindexes table. This column contains the total row count for each table in your database. So, you can use the following select statement instead of SELECT COUNT (*):

SELECT rows FROM sysindexes WHERE id = OBJECT_ID (‘table_name’) AND indid < 2 So, you can improve the speed of such queries in several times.

  • Include SET NOCOUNT ON statement into your stored procedures to stop the message indicating the number of rows affected by a T-SQL statement.

This can reduce network traffic, because your client will not receive the message indicating the number of rows affected by a T-SQL statement.

  • Try to restrict the queries result set by using the WHERE

This can results in good performance benefits, because SQL Server will return to client only particular rows, not all rows from the table(s). This can reduce network traffic and boost the overall performance of the query.

  • Use the select statements with TOP keyword or the SET ROWCOUNT statement, if you need to return only the first n rows.

This can improve performance of your queries, because the smaller result set will be returned. This can also reduce the traffic between the server and the clients.

  • Try to restrict the queries result set by returning only the particular columns from the table, not all table’s columns.

This can results in good performance benefits, because SQL Server will return to client only particular columns, not all table’s columns. This can reduce network traffic and boost the overall performance of the query.

2.avoid more number of triggers on the table
3.unnecessary complicated joins
4.correct use of Group by clause with the select list worst cases Denormalization

T-SQL Queries

  1. 2 tables
Employee Phone
  1. Select all employees who doesn’t have phone?
    SELECT empname FROM Employee WHERE empid NOT IN (SELECT DISTINCT mpid FROM phone)
  2. Select the employee names who is having more than one phone numbers.
  3. SELECT empname FROM employee WHERE (empid IN (SELECT empid
    FROM phone GROUP BY empid HAVING COUNT (empid) > 1))
  4. Select the details of 3 max salaried employees from employee table.
    SELECT TOP 3 empid, salary FROM employee ORDER BY salary DESC
  5. Display all managers from the table.(manager id is same as emp id)
    SELECT empname FROM employee WHERE (empid IN (SELECT DISTINCT mgrid FROM employee))
  6. Write a Select statement to list the Employee Name, Manager Name under a particular manager?
    SELECT e1.empname AS EmpName, e2.empname AS ManagerName
    FROM Employee e1 INNER JOIN Employee e2 ON e1.mgrid = e2.empid
    ORDER BY e2.mgrid
  7. 2 tables emp and phone. emp fields are – empid, name, Ph fields are – empid, ph (office, mobile, home). Select all employees who don’t have any ph nos.
    SELECT * FROM employee LEFT OUTER JOIN phone ON employee.empid =phone.empid WHERE (phone. office IS NULL OR = ‘ ‘)
    AND ( IS NULL OR = ‘ ‘)
    AND (phone.home IS NULL OR phone.home = ‘ ‘)
  8. Find employee who is living in more than one city. Two Tables:
Emp City





SELECT empname, fname, lname FROM employee WHERE (empid IN (SELECT empid FROM city GROUP BY empid HAVING COUNT (empid) > 1))

  1. Find all employees who are living in the same city. (table is same as above)
    SELECT fname FROM employee WHERE (empid IN (SELECT empid
    FROM city a  WHERE city IN (SELECT city FROM city b GROUP BY city HAVING COUNT(city) > 1)))
  2. There is a table named MovieTable with three columns – moviename, person and role. Write a query which gets the movie details where Mr. Amitabh and Mr. Vinod acted and their role is actor.
    SELECT DISTINCT m1.moviename FROM MovieTable m1 INNER JOIN
    MovieTable m2 ON m1.moviename = m2.moviename WHERE (m1.person = ‘amitabh’ AND m2.person = ‘vinod’ OR m2.person = ‘amitabh’ AND m1.person = ‘vinod’) AND (m1.role = ‘actor’) AND (m2.role = ‘actor’) ORDER BY m1.moviename
  3. There are two employee tables named emp1 and emp2. Both contains same structure (salary details). But Emp2 salary details are incorrect and emp1 salary details are correct. So, write a query which corrects salary details of the table emp2
    update a set a.sal=b.sal from emp1 a, emp2 b where a.empid=b.empid
  4. Given a Table named “Students” which contains studentid, subjectid and marks. Where there are 10 subjects and 50 students. Write a Query to find out the Maximum marks obtained in each subject.
  5. In this same tables now write a SQL Query to get the studentid also to combine with previous results.
  6. Three tables – student , course, marks – how do go at finding name of the students who got max marks in the diff courses.
    SELECT, AS coursename, marks.sid, marks.mark FROM marks INNER JOIN student ON marks.sid = student.sid INNER JOIN course ON marks.cid = course.cid
    WHERE (marks.mark = (SELECT MAX(Mark)
    FROM Marks MaxMark WHERE MaxMark.cID = Marks.cID))
  7. There is a table day_temp which has three columns dayid, day and temperature. How do I write a query to get the difference of temperature among each other for seven days of a week?
    SELECT a.dayid, a.dday, a.tempe, a.tempe – b.tempe AS Difference FROM day_temp a INNER JOIN day_temp b ON a.dayid = b.dayid + 1 OR
    Select, from temperature a, temperature b where
  8. There is a table which contains the names like this. a1, a2, a3, a3, a4, a1, a1, a2 and their salaries. Write a query to get grand total salary, and total salaries of individual employees in one query.
    SELECT empid, SUM(salary) AS salary FROM employee
  9. How to know how many tables contains empno as a column in a database?
    SELECT COUNT(*) AS Counter FROM syscolumns
    WHERE (name = ’empno’)
  10. Find duplicate rows in a table? OR I have a table with one column which has many records which are not distinct. I need to find the distinct values from that column and number of times it’s repeated.
    SELECT sid, mark, COUNT(*) AS Counter FROM marks GROUP BY sid, mark HAVING (COUNT(*) > 1)
  11. How to delete the rows which are duplicate (don’t delete both duplicate records).
  12. DELETE yourtable FROM yourtable a
    WHERE (SELECT COUNT(*) FROM yourtable b WHERE b.name1 = a.name1 AND b.age1 = a.age1) > 1 WHILE @@rowcount > 0 DELETE yourtable   FROM yourtable a WHERE (SELECT COUNT(*) FROM yourtable b WHERE b.name1 = a.name1 AND b.age1 = a.age1) > 1
  13. How to find 6th highest salary
    FROM employee ORDER BY salary DESC) a ORDER BY salary
  14. Find top salary among two tables
    SELECT TOP 1 sal FROM (SELECT MAX(sal) AS sal FROM sal1 UNION SELECT MAX(sal) AS sal FROM sal2) a ORDER BY sal DESC
  15. Write a query to convert all the letters in a word to upper case
    SELECT UPPER(‘test’)
  16. Write a query to round up the values of a number. For example even if the user enters 7.1 it should be rounded up to 8.
  17. Write a SQL Query to find first day of month?
    SELECT DATENAME (dw, DATEADD (dd, – DATEPART (dd, GETDATE ()) + 1, GETDATE ())) AS FirstDay
Datepart Abbreviations
year yy, yyyy
quarter qq, q
month mm, m
dayofyear dy, y
day dd, d
week wk, ww
weekday Dw
hour Hh
minute mi, n
second ss, s
millisecond Ms
  1. Table A contains column1 which is primary key and has 2 values (1, 2) and Table B contains column1 which is primary key and has 2 values (2, 3). Write a query which returns the values that are not common for the tables and the query should return one column with 2 records.
    SELECT tbla.a FROM tbla, tblb WHERE tbla.a <> (SELECT tblb.a
    FROM tbla, tblb WHERE tbla.a = tblb.a) UNION SELECT tblb.a
    FROM tbla, tblb WHERE tblb.a <> (SELECT tbla.a FROM tbla, tblb
    WHERE tbla.a = tblb.a)OR (better approach)


  2. There are 3 tables Titles, Authors and Title-Authors (check PUBS db). Write the query to get the author name and the number of books written by that author, the result should start from the author who has written the maximum number of books and end with the author who has written the minimum number of books.
    SELECT authors.au_lname, COUNT(*) AS BooksCount FROM authors INNER JOIN
    titleauthor ON authors.au_id = titleauthor.au_id INNER JOIN
    titles ON titles.title_id = titleauthor.title_id GROUP BY authors.au_lname ORDER BY BooksCount DESC
  3. List all products with total quantity ordered, if quantity ordered is null show it as 0.
    product ON [order].prodid = product.prodid GROUP BY name
    coke 60
    mirinda 0
    pepsi 10
  4. ANY, SOME, or ALL?cxx
    ALL means greater than every value–in other words, greater than the maximum value. For example, >ALL (1, 2, 3) means greater than 3.
    ANY means greater than at least one value, that is, greater than the minimum. So >ANY (1, 2, 3) means greater than 1. SOME is an SQL-92 standard equivalent for ANY.

    • IN & = (difference in correlated sub query)
  5. Given a scenario that I have a 10 Clustered Index in a Table to all their 10 Columns. What are the advantages and disadvantages?
    A: Only 1 clustered index is possible.
  6. How can I enforce to use particular index?
    You can use index hint (index=<index_name>) after the table name.
    SELECT au_lname FROM authors (index=aunmind)
  7. What is sorting and what is the difference between sorting & clustered indexes?
    The ORDER BY clause sorts query results by one or more columns up to 8,060 bytes. This will happen by the time when we retrieve data from database. Clustered indexes physically sorting data, while inserting/updating the table.
  8. Difference between char and nvarchar / char and varchar data-type?
    char[(n)] – Fixed-length non-Unicode character data with length of n bytes. n must be a value from 1 through 8,000. Storage size is n bytes. The SQL-92 synonym for char is character.
    nvarchar(n) – Variable-length Unicode character data of n characters. n must be a value from 1 through 4,000. Storage size, in bytes, is two times the number of characters entered. The data entered can be 0 characters in length. The SQL-92 synonyms for nvarchar are national char varying and national character varying.
    varchar[(n)] – Variable-length non-Unicode character data with length of n bytes. n must be a value from 1 through 8,000. Storage size is the actual length in bytes of the data entered, not n bytes. The data entered can be 0 characters in length. The SQL-92 synonyms for varchar are char varying or character varying.
  9. GUID datasize?
  10. How GUID becoming unique across machines?
    To ensure uniqueness across machines, the ID of the network card is used (among others) to compute the number.
  11. Can I improve performance by using the ANSI-style joins instead of the old-style joins?
    Code Example 1:
    select, from sysobjects o, sysindexes i
    where =

Code Example 2:
select, from sysobjects o inner join sysindexes i
on =

You will not get any performance gain by switching to the ANSI-style JOIN syntax.
Using the ANSI-JOIN syntax gives you an important advantage:

Because the join logic is cleanly separated from the filtering criteria, you can understand the query logic more quickly.
The SQL Server old-style JOIN executes the filtering conditions before executing the joins, whereas the ANSI-style JOIN reverses this procedure (join logic precedes filtering).
Perhaps the most compelling argument for switching to the ANSI-style JOIN is that Microsoft has explicitly stated that SQL Server will not support the old-style OUTER JOIN syntax indefinitely. Another important consideration is that the ANSI-style JOIN supports query constructions that the old-style JOIN syntax does not support.

  1. How do I mark the stored procedure to automatic execution?
    You can use the sp_procoption system stored procedure to mark the stored procedure to automatic execution when the SQL Server will start. Only objects in the master database owned by dbo can have the startup setting changed and this option is restricted to objects that have no parameters.
    USE master
    EXEC sp_procoption ‘indRebuild’, ‘startup’, ‘true’)
  2. How will know whether the SQL statements are executed?
    When used in a stored procedure, the RETURN statement can specify an integer value to return to the calling application, batch, or procedure. If no value is specified on RETURN, a stored procedure returns the value 0.  The stored procedures return a value of 0 when no errors were encountered. Any nonzero value indicates an error occurred.
  3. Why one should not prefix user stored procedures with sp_?
    It is strongly recommended that you do not create any stored procedures using sp_ as a prefix. SQL Server always looks for a stored procedure beginning with sp_ in this order:

    • The stored procedure in the master database.
    • The stored procedure based on any qualifiers provided (database name or owner).
    • The stored procedure using dbo as the owner, if one is not specified.

Therefore, although the user-created stored procedure prefixed with sp_ may exist in the current database, the master database is always checked first, even if the stored procedure is qualified with the database name.

  1. What can cause a Stored procedure execution plan to become invalidated and/or fall out of cache?
    1. Server restart
    2. Plan is aged out due to low use
    3. DBCC FREEPROCCACHE (sometime desired to force it)
  2. When do one need to recompile stored procedure?
    if a new index is added from which the stored procedure might benefit, optimization does not automatically happen (until the next time the stored procedure is run after SQL Server is restarted).
  3. I have Two Stored Procedures SP1 and SP2 as given below. How the Transaction works, whether SP2 Transaction succeeds or fails?
    EXEC SP2
    commit tran
    Both will get roll backed.
    commit tran
    Both will get roll backed.
  5. How will you handle Errors in SQL Stored Procedure?
    INSERT NonFatal VALUES (@Column2)
    IF @@ERROR <>0
    PRINT ‘Error Occured’
  6. How will you raise an error in SQL?

Returns a user-defined error message and sets a system flag to record that an error has occurred. Using RAISERROR, the client can either retrieve an entry from the sysmessages table or build a message dynamically with user-specified severity and state information. After the message is defined it is sent back to the client as a server error message.

  1. I have a stored procedure like
    commit tran
    create table a()
    insert into table b

    rollback tran
    what will be the result? Is table created? data will be inserted in table b?
  2. How you will return XML from Stored Procedure?
    You use the FOR XML clause of the SELECT statement, and within the FOR XML clause you specify an XML mode: RAW, AUTO, or EXPLICIT.
  3. Can a Stored Procedure call itself (recursive). If so then up to what level and can it be control?
    Stored procedures are nested when one stored procedure calls another. You can nest stored procedures up to 32 levels. The nesting level increases by one when the called stored procedure begins execution and decreases by one when the called stored procedure completes execution. Attempting to exceed the maximum of 32 levels of nesting causes the whole calling stored procedure chain to fail. The current nesting level for the stored procedures in execution is stored in the @@NESTLEVEL function.
    USE master
    IF OBJECT_ID(‘dbo.sp_calcfactorial’) IS NOT NULL
    DROP PROC dbo.sp_calcfactorial
    CREATE PROC dbo.sp_calcfactorial
    @base_number int, @factorial int OUT
    DECLARE @previous_number int
    IF (@base_number<2) SET @factorial=1 — Factorial of 0 or 1=1
    SET @previous_number=@base_number-1
    EXEC dbo.sp_calcfactorial @previous_number, @factorial OUT — Recursive call
    IF (@factorial=-1) RETURN(-1) — Got an error, return
    SET @factorial=@factorial*@base_number
    GOcalling proc.
    DECLARE @factorial int
    EXEC dbo.sp_calcfactorial 4, @factorial OUT
    SELECT @factorial
  4. Nested Triggers
    Triggers are nested when a trigger performs an action that initiates another trigger, which can initiate another trigger, and so on. Triggers can be nested up to 32 levels, and you can control whether triggers can be nested through the nested triggers server configuration option.
  5. What is an extended stored procedure? Can you instantiate a COM object by using T-SQL?
    An extended stored procedure is a function within a DLL (written in a programming language like C, C++ using Open Data Services (ODS) API) that can be called from T-SQL, just the way we call normal stored procedures using the EXEC statement.
  6. Difference between view and stored procedure?
    Views can have only select statements (create, update, truncate, delete statements are not allowed) Views cannot have “select into”, “Group by” “Having”, ”Order by”
  7. Difference between trigger and stored procedure?
    Trigger will get execute automatically when an UPDATE, INSERT, or DELETE statement is issued against a table or view.
    We have to call stored procedure manually, or it can execute automatic when the SQL Server starts (You can use the sp_procoption system stored procedure to mark the stored procedure to automatic execution when the SQL Server will start.
  8. The following trigger generates an e-mail whenever a new title is added.
    CREATE TRIGGER reminder
    ON titles
    EXEC master..xp_sendmail ‘MaryM’, ‘New title, mention in the next report to distributors.’
  9. Drawback of trigger? Its alternative solution?
    Triggers are generally used to implement business rules, auditing. Triggers can also be used to extend the referential integrity checks, but wherever possible, use constraints for this purpose, instead of triggers, as constraints are much faster.
  10. Does the View occupy memory space? No
  11. Can u drop a table if it has a view?
    Views or tables participating in a view created with the SCHEMABINDING clause cannot be dropped. If the view is not created using SCHEMABINDING, then we can drop the table.
  12. Why doesn’t SQL Server permit an ORDER BY clause in the definition of a view?
    SQL Server excludes an ORDER BY clause from a view to comply with the ANSI SQL-92 standard. Because analyzing the rationale for this standard requires a discussion of the underlying structure of the structured query language (SQL) and the mathematics upon which it is based, we can’t fully explain the restriction here. However, if you need to be able to specify an ORDER BY clause in a view, consider using the following workaround
    USE pubs
    CREATE VIEW AuthorsByName
    SELECT TOP 100 PERCENT * FROM authors ORDER BY au_lname, au_fname
    The TOP construct, which Microsoft introduced in SQL Server 7.0, is most useful when you combine it with the ORDER BY clause. The only time that SQL Server supports an ORDER BY clause in a view is when it is used in conjunction with the TOP keyword. (Note that the TOP keyword is a SQL Server extension to the ANSI SQL-92 standard.)TRANSACTION


  1. What is Transaction?
    A transaction is a sequence of operations performed as a single logical unit of work. A logical unit of work must exhibit four properties, called the ACID (Atomicity, Consistency, Isolation, and Durability) properties, to qualify as a transaction:

    • Atomicity – A transaction must be an atomic unit of work; either all of its data modifications are performed or none of them is performed.
    • Consistency – When completed, a transaction must leave all data in a consistent In a relational database, all rules must be applied to the transaction’s modifications to maintain all data integrity. All internal data structures, such as B-tree indexes or doubly-linked lists, must be correct at the end of the transaction.
    • Isolation – Modifications made by concurrent transactions must be isolated from the modifications made by any other concurrent transactions. A transaction either sees data in the state it was in before another concurrent transaction modified it, or it sees the data after the second transaction has completed, but it does not see an intermediate state. This is referred to as serializability because it results in the ability to reload the starting data and replay a series of transactions to end up with the data in the same state it was in after the original transactions were performed.
    • Durability – After a transaction has completed, its effects are permanently in place in the system. The modifications persist even in the event of a system failure.
  2. After one Begin Transaction a truncate statement and a RollBack statements are there. Will it be rollbacked? Since the truncate statement does not perform logged operation how does it RollBack?
    It will rollback.
  3. Given a SQL like
    Begin Tran
    Select @@Rowcount
    Begin Tran
    Select @@Rowcount
    Begin Tran
    Select @@Rowcount
    Commit Tran
    Select @@Rowcount
    Select @@Rowcount
    Select @@Rowcount
    What is the value of @@Rowcount at each stmt levels?
    Ans : 0 – zero.
    @@ROWCOUNT – Returns the number of rows affected by the last statement.
    @@TRANCOUNT – Returns the number of active transactions for the current connection.
    Each Begin Tran will add count, each commit will reduce count and ONE rollback will make it 0.


  1. What are the constraints for Table Constraints define rules regarding the values allowed in columns and are the standard mechanism for enforcing integrity. SQL Server 2000 supports five classes of constraints.
  2. There are 50 columns in a table. Write a query to get first 25 columns
    Ans: Need to mention each column names.
  3. How to list all the tables in a particular database?
    USE pubs
  4. What is Dynamic Cursor? Suppose, I have a dynamic cursor attached to table in a database.  I have another means by which I will modify the table.  What do you think will the values in the cursor be?
    Dynamic cursors reflect all changes made to the rows in their result set when scrolling through the cursor. The data values, order, and membership of the rows in the result set can change on each fetch. All UPDATE, INSERT, and DELETE statements made by all users are visible through the cursor. Updates are visible immediately if they are made through the cursor using either an API function such as SQLSetPos or the Transact-SQL WHERE CURRENT OF clause. Updates made outside the cursor are not visible until they are committed, unless the cursor transaction isolation level is set to read uncommitted.
  5. What is DATEPART?
    Returns an integer representing the specified datepart of the specified date.
  6. Difference between Delete and Truncate?
    TRUNCATE TABLE is functionally identical to DELETE statement with no WHERE clause: both remove all rows in the table.
    (1) But TRUNCATE TABLE is faster and uses fewer system and transaction log resources than DELETE. The DELETE statement removes rows one at a time and records an entry in the transaction log for each deleted row. TRUNCATE TABLE removes the data by deallocating the data pages used to store the table’s data, and only the page deallocations are recorded in the transaction log.
    (2) Because TRUNCATE TABLE is not logged, it cannot activate a trigger.
    (3) The counter used by an identity for new rows is reset to the seed for the column. If you want to retain the identity counter, use DELETE instead.
    Of course, TRUNCATE TABLE can be rolled back.
  7. What are global variables? Tell me some of them?
    Transact-SQL global variables are a form of function and are now referred to as functions.
    ABS – Returns the absolute, positive value of the given numeric expression.
  8. What is DDL?
    Data definition language (DDL) statements are SQL statements that support the definition or declaration of database objects (for example, CREATE TABLE, DROP TABLE, and ALTER TABLE).
    You can use the ADO Command object to issue DDL statements. To differentiate DDL statements from a table or stored procedure name, set the CommandType property of the Command object to adCmdText. Because executing DDL queries with this method does not generate any recordsets, there is no need for a Recordset object.
  9. What is DML?
    Data Manipulation Language (DML), which is used to select, insert, update, and delete data in the objects defined using DDL
  10. What are keys in RDBMS? What is a primary key/ foreign key?
    There are two kinds of keys.
    A primary key is a set of columns from a table that are guaranteed to have unique values for each row of that table.
    Foreign keys are attributes of one table that have matching values in a primary key in another table, allowing for relationships between tables.
  11. What is the difference between Primary Key and Unique Key?
    Both primary key and unique key enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn’t allow NULLs, but unique key allows one NULL
  12. Define candidate key, alternate key, composite key?
    A candidate key is one that can identify each row of a table uniquely. Generally a candidate key becomes the primary key of the table. If the table has more than one candidate key, one of them will become the primary key, and the rest are called alternate keys.
    A key formed by combining at least two or more columns is called composite key.
  13. What is the Referential Integrity?
    Referential integrity refers to the consistency that must be maintained between primary and foreign keys, i.e. every foreign key value must have a corresponding primary key value.
  14. What are defaults? Is there a column to which a default can’t be bound?
    A default is a value that will be used by a column, if no value is supplied to that column while inserting data. IDENTITY columns and timestamp columns can’t have defaults bound to them.
  15. What is the use of shell commands? xp_cmdshell
    Executes a given command string as an operating-system command shell and returns any output as rows of text. Grants nonadministrative users permissions to execute xp_cmdshell.
  16. What is use of shrink database?
    Microsoft® SQL Server 2000 allows each file within a database to be shrunk to remove unused pages. Both data and transaction log files can be shrunk.
  17. How do you differentiate Local and Global Temporary table?
    You can create local and global temporary tables. Local temporary tables are visible only in the current session; global temporary tables are visible to all sessions. Prefix local temporary table names with single number sign (#table_name), and prefix global temporary table names with a double number sign (##table_name). SQL statements reference the temporary table using the value specified for table_name in the CREATE TABLE statement:
    INSERT INTO #MyTempTable VALUES (1)
  18. How the Exists keyword works in SQL Server?
    USE pubs
    SELECT au_lname, au_fname FROM authors WHERE exists (SELECT *
    FROM publishers  WHERE =
    When a subquery is introduced with the keyword EXISTS, it functions as an existence test. The WHERE clause of the outer query tests for the existence of rows returned by the subquery. The subquery does not actually produce any data; it returns a value of TRUE or FALSE.
  19. ANY?
    USE pubs
    SELECT au_lname, au_fname FROM authors WHERE city = ANY
    (SELECT city FROM publishers)
  20. To select date part only
    SELECT CONVERT(char(10),GetDate(),101)
    –to select time part only
    SELECT right(GetDate(),7)
  21. What is normalization? Explain different levels of normalization? Explain Third normalization form with an example?
    The process of refining tables, keys, columns, and relationships to create an efficient database is called normalization. This should eliminates unnecessary duplication and provides a rapid search path to all necessary information.
    Some of the benefits of normalization are:

    • Data integrity (because there is no redundant, neglected data)
    • Optimized queries (because normalized tables produce rapid, efficient joins)
    • Faster index creation and sorting (because the tables have fewer columns)
    • Faster UPDATE performance (because there are fewer indexes per table)
    • Improved concurrency resolution (because table locks will affect less data)
    • Eliminate redundancy

There are a few rules for database normalization. Each rule is called a “normal form.” If the first rule is observed, the database is said to be in “first normal form.” If the first three rules are observed, the database is considered to be in “third normal form.” Although other levels of normalization are possible, third normal form is considered the highest level necessary for most applications.

First Normal Form (1NF)

  • Eliminate repeating groups in individual tables
  • Create a separate table for each set of related data.
  • Identify each set of related data with a primary key.

Do not use multiple fields in a single table to store similar data.

  Subordinate1 Subordinate2 Subordinate3 Subordinate4
Bob Jim Mary Beth  
Mary Mike Jason Carol Mark
Jim Alan      


Eliminate duplicative columns from the same table.  Clearly, the Subordinate1 Subordinate4 Columns are duplicative. What happens when we need to add or remove a subordinate?


Bob Jim, Mary, Beth
Mary Mike, Jason, Carol, Mark
Jim Alan

This solution is closer, but it also falls short of the mark. The subordinates column is still duplicative and non-atomic. What happens when we need to add or remove a subordinate? We need to read and write the entire contents of the table. That’s not a big deal in this situation, but what if one manager had one hundred employees? Also, it complicates the process of selecting data from the database in future queries.


Bob Jim
Bob Mary
Bob Beth
Mary Mike
Mary Jason
Mary Carol
Mary Mark
Jim Alan

         Second Normal Form (2NF)

  • Create separate tables for sets of values that apply to multiple records.
  • Relate these tables with a foreign key.

Records should not depend on anything other than a table’s primary key (a compound key, if necessary).

For example, consider a customer’s address in an accounting system. The address is needed by the Customers table, but also by the Orders, Shipping, Invoices, Accounts Receivable, and Collections tables. Instead of storing the customer’s address as a separate entry in each of these tables, store it in one place, either in the Customers table or in a separate Addresses table.

Third Normal Form (3NF)

  • Eliminate fields that do not depend on the key.

Values in a record that are not part of that record’s key do not belong in the table. In general, any time the contents of a group of fields may apply to more than a single record in the table, consider placing those fields in a separate table.
For example, in an Employee Recruitment table, a candidate’s university name and address may be included. But you need a complete list of universities for group mailings. If university information is stored in the Candidates table, there is no way to list universities with no current candidates. Create a separate Universities table and link it to the Candidates table with a university code key.
Another Example :

MemberId Name Company CompanyLoc
1 John Smith ABC Alabama
2 Dave Jones MCI Florida

The Member table satisfies first normal form – it contains no repeating groups. It satisfies second normal form – since it doesn’t have a multivalued key. But the key is MemberID, and the company name and location describe only a company, not a member. To achieve third normal form, they must be moved into a separate table. Since they describe a company, CompanyCode becomes the key of the new “Company” table.

The motivation for this is the same for second normal form: we want to avoid update and delete anomalies. For example, suppose no members from the IBM were currently stored in the database. With the previous design, there would be no record of its existence, even though 20 past members were from IBM.

Member Table


Name CID
1 John Smith 1
2 Dave Jones 2

Company Table


Name Location
1 ABC Alabama
2 MCI Florida

Boyce-Codd Normal Form (BCNF)
A relation is in Boyce/Codd normal form if and only if the only determinants are candidate key. Its a different version of 3NF, indeed, was meant to replace it. [A determinant is any attribute on which some other attribute is (fully) functionally dependent.]

4th Normal Form (4NF)

A table is in 4NF if it is in BCNF and if it has no multi-valued dependencies. This applies primarily to key-only associative tables, and appears as a ternary relationship, but has incorrectly merged 2 distinct, independent relationships.
Eg: This could be any 2 M:M relationships from a single entity. For instance, a member could know many software tools, and a software tool may be used by many members. Also, a member could have recommended many books, and a book could be recommended by many members.

Software   Member   Book

The correct solution, to cause the model to be in 4th normal form, is to ensure that all M:M relationships are resolved independently if they are indeed independent.

Software   Member software   Member  


Member Book  



5th Normal Form (5NF)(PJNF)
A table is in 5NF, also called “Projection-Join Normal Form”, if it is in 4NF and if every join dependency in the table is a consequence of the candidate keys of the table.

Domain/Key Normal form (DKNF). A key uniquely identifies each row in a table. A domain is the set of permissible values for an attribute. By enforcing key and domain restrictions, the database is assured of being freed from modification anomalies. DKNF is the normalization level that most designers aim to achieve.

Remember, these normalization guidelines are cumulative.  For a database to be in 2NF, it must first fulfill all the criteria of a 1NF database.

  1. What is denormalization and when would you go for it?
    As the name indicates, denormalization is the reverse process of normalization. It’s the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.
  2. How can I randomly sort query results?
    To randomly order rows, or to return x number of randomly chosen rows, you can use the RAND function inside the SELECT statement. But the RAND function is resolved only once for the entire query, so every row will get same value. You can use an ORDER BY clause to sort the rows by the result from the NEWID function, as the following code shows:
    SELECT * FROM Northwind..Orders ORDER BY NEWID()
  3. sp_who
    Provides information about current Microsoft® SQL Server™ users and processes. The information returned can be filtered to return only those processes that are not idle.
  4. How to find dependents of a table?
    Verify dependencies with sp_depends before dropping an object
  5. What is the difference between a CONSTRAINT AND RULE?
    Rules are a backward-compatibility feature that perform some of the same functions as CHECK constraints. CHECK constraints are the preferred, standard way to restrict the values in a column. CHECK constraints are also more concise than rules; there can only be one rule applied to a column, but multiple CHECK constraints can be applied. CHECK constraints are specified as part of the CREATE TABLE statement, while rules are created as separate objects and then bound to the column.
  6. How to call a COM dll from SQL Server 2000?
    sp_OACreate – Creates an instance of the OLE object on an instance of Microsoft® SQL Server
    progid, | clsid,
    objecttoken OUTPUT
    [ , context ]

context Specifies the execution context in which the newly created OLE object runs. If specified, this value must be one of the following:
= In-process (.dll) OLE server only
4 = Local (.exe) OLE server only
5 = Both in-process and local OLE server allowed

A. Use Prog ID – This example creates a SQL-DMO SQLServer object by using its ProgID.

DECLARE @object intDECLARE @hr intDECLARE @src varchar(255), @desc varchar(255)EXEC @hr = sp_OACreate ‘SQLDMO.SQLServer’, @object OUTIF @hr <> 0BEGIN   EXEC sp_OAGetErrorInfo @object, @src OUT, @desc OUT    SELECT hr=convert(varbinary(4),@hr), Source=@src, Description=@desc    RETURNEND

  1. Use CLSID – This example creates a SQL-DMO SQLServer object by using its CLSID.

DECLARE @object intDECLARE @hr intDECLARE @src varchar(255), @desc varchar(255)EXEC @hr = sp_OACreate ‘{00026BA1-0000-0000-C000-000000000046}’,    @object OUTIF @hr <> 0BEGIN   EXEC sp_OAGetErrorInfo @object, @src OUT, @desc OUT    SELECT hr=convert(varbinary(4),@hr), Source=@src, Description=@desc    RETURNEND

  1. Difference between sysusers and syslogins?
    sysusers – Contains one row for each Microsoft® Windows user, Windows group, Microsoft SQL Server™ user, or SQL Server role in the database.
    syslogins – Contains one row for each login account.
  2. What is the row size in SQL Server 2000?
    8060 bytes.
  3. How will you find structure of table, all tables/views in one db, all dbs?
    //structure of table
    sp_helpdb tbl_emp

    list of all databases
    SELECT * FROM master.dbo.sysdatabases//details about database pubs. .mdf, .ldf file locations, size of database
    sp_helpdb pubs

    //lists all tables under current database
    SELECT * FROM information_schema.tables WHERE (table_type = ‘base table’)
    SELECT * FROM sysobjects WHERE type = ‘U’ //faster

  4. What is the system function to get the current user’s user id?
    USER_ID(). Also check out other system functions like USER_NAME(), SYSTEM_USER, SESSION_USER, CURRENT_USER, USER, SUSER_SID(), HOST_NAME().
  5. What are the series of steps that happen on execution of a query in a Query Analyzer?
    1) Syntax checking 2) Parsing 3) Execution plan
  6. Which event (Check constraints, Foreign Key, Rule, trigger, Primary key check) will be performed last for integrity check?
    Identity Insert Check
    Nullability constraint
    Data type check
    Instead of trigger
    Primary key
    Check constraint
    Foreign key
    DML Execution (update statements)
    After Trigger
  7. How will you show many to many relation in SQL?
    Create 3rd table with 2 columns which having one to many relation to these tables.
  8. When a query is sent to the database and an index is not being used, what type of execution is taking place?
    A table scan.
  9. What is #, ##, @, @@ means?
    @@ – System variables 2) @ – user defined variables
  10. What is the difference between a Local temporary table and a Global temporary table? How is each one denoted?
    Local temporary table will be accessible to only current user session, its name will be preceded with a single hash (#mytable)
    Global temporary table will be accessible to all users, & it will be dropped only after ending of all active connections, its name will be preceded with double hash (##mytable)


  1. What is the output of DBCC Showcontig statement?
    Displays fragmentation information for the data and indexes of the specified table.
  2. About SQL Command line executables
Bcp      : console, isql , sqlagent, sqldiag, sqlmaint, sqlservr, vswitch
Dtsrun : dtswiz, isqlw, itwiz, odbccmpt, osql, rebuildm, sqlftwiz
Distrib  : logread, replmerg, snapshot



  1. What is DTC?
    The Microsoft Distributed Transaction Coordinator (MS DTC) is a transaction manager that allows client applications to include several different sources of data in one transaction. MS DTC coordinates committing the distributed transaction across all the servers enlisted in the transaction.
  2. What is DTS? Any drawbacks in using DTS?
    Microsoft® SQL Server™ 2000 Data Transformation Services (DTS) is a set of graphical tools and programmable objects that lets you extract, transform, and consolidate data from disparate sources into single or multiple destinations.
  3. What are the different ways of moving data/databases between servers and databases in SQL Server?
    There are lots of options available, you have to choose your option depending upon your requirements. Some of the options you have are: BACKUP/RESTORE, detaching and attaching databases, replication, DTS, BCP, logshipping, INSERT…SELECT, SELECT…INTO, creating INSERT scripts to generate data.
  4. How will I export database?
    Through DTS – Import/Export wizard
    Backup – through Complete/Differential/Transaction Log
  5. How to export database at a particular time, every week?
    Backup – Schedule
    DTS – Schedule
    Jobs – create a new job
  6. How do you load large data to the SQL server database? bcp
  7. How do you transfer data from text file to database (other than DTS)? bcp
  8. What is OSQL and ISQL utility?
    The osql utility allows you to enter Transact-SQL statements, system procedures, and script files. This utility uses ODBC to communicate with the server.
    The isql utility allows you to enter Transact-SQL statements, system procedures, and script files; and uses DB-Library to communicate with Microsoft® SQL Server™ 2000.
    All DB-Library applications, such as isql, work as SQL Server 6.5–level clients when connected to SQL Server 2000. They do not support some SQL Server 2000 features.
    The osql utility is based on ODBC and does support all SQL Server 2000 features. Use osql to run scripts that isql cannot run.
  9. Different Authentication modes in Sql server? If a user is logged under windows authentication mode, how to find his userid?
    There are Three Different authentication modes in SQLSERVER.
  1. Windows Authentication Mode
  2. SQL Server Authentication Mode
  3. Mixed Authentication Mode

“system_user” system function in sqlserver to fetch the logged on user name.

  1. Give the connection strings from front-end for both type logins(windows,sqlserver)?
    This are specifically for sqlserver not for any other RDBMS
    Data Source=MySQLServer;Initial Catalog=NORTHWIND;Integrated Security=SSPI (windows)
    Data Source=MySQLServer;Initial Catalog=NORTHWIND;Uid=” ”;Pwd=” ”(sqlserver)
  2. What are three SQL keywords used to change or set someone’s permissions?
    Grant, Deny and Revoke ADMINISTRATION


  1. Different types of Backups?
    • A full database backup is a full copy of the database.
    • A transaction log backup copies only the transaction log.
    • A differential backup copies only the database pages modified after the last full database backup.
    • A file or filegroup restore allows the recovery of just the portion of a database that was on the failed disk.
  2. What are ‘jobs’ in SQL Server? How do we create one? What is tasks?
    Using SQL Server Agent jobs, you can automate administrative tasks and run them on a recurring basis.
  3. What is database replication? What are the different types of replication you can set up in SQL Server? How are they used? What is snapshot replication how is it different from Transactional replication?
    Replication is the process of copying/moving data between databases on the same or different servers. SQL Server supports the following types of replication scenarios:

Snapshot replication : It distributes data exactly as it appears at a specific moment in time and doesn’t monitor for updates. It can be used when data changes are infrequent. It is often used for browsing data such as price lists, online catalog, or data for decision support where the current data is not required and data is used as read only.

Transactional replication: (with immediate updating subscribers, with queued updating subscribers) – With this an initial snapshot of data is applied, and whenever data modifications are made at the publisher, the individual transactions are captured and propagated to the subscribers.

Merge replication: It is the process of distributing the data between publisher and subscriber, it allows the publisher and subscriber to update the data while connected or disconnected, and then merging the updates between the sites when they are connected.

  1. How can u look at what are the process running on SQL server? How can you kill a process in SQL server?
    • Expand a server group, and then expand a server.
    • Expand Management, and then expand Current Activity.
    • Click Process Info. The current server activity is displayed in the details pane.

In the details pane, right-click a Process ID, and then click Kill Process.

  1. What is RAID and what are different types of RAID configurations?
    RAID stands for Redundant Array of Inexpensive Disks, used to provide fault tolerance to database servers. There are six RAID levels 0 through 5 offering different levels of performance, fault tolerance.
  1. How to determine the service pack currently installed on SQL Server?
    The global variable @@Version stores the build number of the sqlservr.exe, which is used to determine the service pack installed.
    eg: Microsoft SQL Server 2000 – 8.00.760 (Intel X86) Dec 17 2002 14:22:05 Copyright (c) 1988-2003 Microsoft Corporation Enterprise Edition on Windows NT 5.0 (Build 2195: Service Pack 3)
  2. What is the STUFF Function and how does it differ from the REPLACE function?
    STUFF – Deletes a specified length of characters and inserts another set of characters at a specified starting point.
    SELECT STUFF(‘abcdef’, 2, 3, ‘ijklmn’)
    Here is the result set:

REPLACE – Replaces all occurrences of the second given string expression in the first string expression with a third expression.
SELECT REPLACE(‘abcdefghicde’,’cde’,’xxx’)
Here is the result set:

  1. What is the purpose of UPDATE STATISTICS?
    Updates information about the distribution of key values for one or more statistics groups (collections) in the specified table or indexed view.
  2. What is a tuple?
    A tuple is an instance of data within a relational database.
  3. sp_configure commands?
    Displays or changes global configuration settings for the current server.
  4. What are sequence diagrams? What you will get out of this sequence diagrams?
    Sequence diagrams document the interactions between classes to achieve a result, such as a use case. Because UML is designed for object-oriented programming, these communications between classes are known as messages. The sequence diagram lists objects horizontally, and time vertically, and models these messages over time.
  5. How do we open SQL Server in single user mode?
    We can accomplish this in any of the three ways given below :-

    • From Command Prompt :-
      sqlservr -m
    • From Startup Options :-
      Go to SQL Server Properties by right-clicking on the Server name in the Enterprise
      Under the ‘General’ tab, click on ‘Startup Parameters’.
      Enter a value of -m in the Parameter.
    • From Registry :-
      Go to HKEY_LOCAL_MACHINE\Software\Microsoft\MSSQLServer\MSSQLServer\Parameters.
      Add new string value.
      Specify the ‘Name’ as SQLArg(n) & ‘Data’ as -m.
      Where n is the argument number in the list of arguments.
  6. How can I convert data in a Microsoft Access table into XML format?
    The following applications can help you convert Access data into XML format: Access 2002, ADO5, and SQLXML. Access 2002 (part of Microsoft Office XP) enables you to query or save a table in XML format. You might be able to automate this process. ADO 2.5 and later enables you to open the data into a recordset, then persist the recordset in XML format, as the following code shows:
    rs.Save “c:\rs.xml”, adPersistXML
    You can use linked servers to add the Access database to your SQL Server 2000 database so you can run queries from within SQL Server to retrieve data. Then, through HTTP, you can use the SQLXML technology to extract the Access data in the XML format you want.
  7. @@IDENTITY ?

Ans: Returns the last-inserted identity value.