What is a relational database?

relational database (RDB) is a collective set of multiple data sets organized by tablesrecords and columns. RDBs establish a well-defined relationship between database tables. Tables communicate and share information, which facilitates data searchability, organization and reporting.

RDBs use Structured Query Language (SQL), which is a standard user application that provides an easy programming interface for database interaction.

Relational databases are based on the relational modelan intuitive, straightforward way of representing data in tables. In a relational database, each row in the table is a record with a unique ID called the key. The columns of the table hold attributes of the data, and each record usually has a value for each attribute, making it easy to establish the relationships among data points.

Benefits of Relational Databases:

  • Data Consistency
  • Commitment and Atomicity
  • Stored Procedures and Relational Databases
  • Database Locking and Concurrency

Relational Database Terms

Below are the unique terms and specific definitions that will help you understand what a RDB can do and how it works:

Row : A set of data constituting a single item.

For example, the data for a single employee (e.g. first name, last name, employee ID, hire date, work location, etc.) of a company would be displayed in a row. A row can also be called a record, an entity, or a tuple.

Column: Labels for elements of rows. A column gives context to the information contained in rows. For an employee database, the column headers could be the items listed above for employees. A column is also known as an attribute or a field.

Table: A group of rows that match the parameters set up for the table. The data in a table must all be related. An employee database may have separate tables for active employees, retired employees, and former employees. A table is also known as a relation or base revelar.

View: A set of data based on a query via the RDBMS; also known as result set or derived revelar.

Domain: The set of possible values for a given column. For example, the phone number and ZIP code columns would be numbers, while first and last names would be limited to letters.

Constraint: A narrowing of a domain. For example, the domain of the work location on a employee record would be alphanumeric, but it could be restricted to a predefined list rather than being a free-form field. The phone number field would be constrained to 10 digits.

Primary key: The unique identifier of a row in a table.

Foreign key: The unique identifier of a row in another table.

Distributed Database: A database that stores data in multiple locations, rather than on a single hard drive or server.

TYPES OF DATABASE RELATIONSHIPS

The power of a relational database is in the links and relations. By connecting rows in different tables through the use of primary and foreign keys, you can create views, reports, and other slices of information to serve your organization. There are three primary types of database relationships:

One-to-One: One row in one table is connected to one and only one row in another table. For example, a Social Security number is linked to a single employee.

One-to-Many: One row in one table is connected to zero, one, or more than one rows in another table. For example, one work location can be linked to many employees.

Many-to-Many: Zero, one, or many rows in one table are linked to zero, one, or many rows in another table. For example, multiple employees can be assigned to multiple projects.

What is a subquery in SQL?

SubQuery is a query within another query. The outer query is called as main query and inner query is called as SubQuery.

The SubQuery generally executes first, and its output is used to complete the query condition for the main or outer query. Subquery must be enclosed in parentheses.

Subqueries are on the right side of the comparison operator. You can place the Subquery in a number of SQL clausesWHERE clauseHAVING clauseFROM clause.

Subqueries can be used with SELECTUPDATEINSERTDELETE statements along with expression operator. It could be equality operator or comparison operator such as =, >, =, <= and Like operator.

ORDER BY command cannot be used in a SubQueryGROUPBY command can be used to perform same function as ORDER BY command.

A Sample Syntax Example for SubQuery:

SELECT column_name

FROM table_name

WHERE column_name expression operator

( SELECT COLUMN_NAME from TABLE_NAME WHERE … );

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What do you mean by Table and Field in SQL?

Tables : In Relational database model, a table is a collection of data elements organised in terms of rows and columns. A table is also considered as a convenient representation of relations. Table is the most simplest form of data storage. Below is an example of an Employee table.

Tuple or Record or Row : A single entry in a table is called a Tuple or Record or Row. A tuple in a table represents a set of related data. For example, the above Employee table has 4 tuples/records/rows.

Following is an example of single record or tuple.

Fields : A field is part of a record and contains a single piece of data for the subject of the record. In the employee table, each record contains four fields. ID, Name, Age, Salary are fields in the table.

What is Power BI ?

Kindly refer the below video on What is Power BI and it’s uses.

Power BI is a business analytics service by Microsoft. It is a cloud-based, elegant end-to-end business analytics tool that enables anyone to visualize, analyze, forecast any type of data with greater speed, efficiency, and understanding.

Power BI provides cloud-based BI services, known as “Power BI Services“, along with a desktop based interface, called “Power BI Desktop”. It offers data warehouse capabilities including data preparation, data discovery and interactive dashboards. Microsoft released an additional service called Power BI Embedded on its Azure cloud platform. One main differentiator of the product is the ability to load custom visualizations.

Key components:

Power BI Desktop : The Windows-desktop-based application for PCs and desktops, primarily for designing and publishing reports to the Service.

Power BI Service : The SaaS (software as a service) based online service (formerly known as Power BI for Office 365, now referred to as PowerBI.com or simply Power BI).

Power BI Mobile Apps : The Power BI Mobile apps for Android and iOS devices, as well as for Windows phones and tablets.

Power BI Gateway : Gateways used to sync external data in and out of Power BI. In Enterprise mode, can also be used by Flows and PowerApps in Office 365.

Power BI Embedded : Power BI REST API can be used to build dashboards and reports into the custom applications that serves Power BI users, as well as non-Power BI users.

Power BI Report Server : An On-Premises Power BI Reporting solution for companies that won’t or can’t store data in the cloud-based Power BI Service.

Power BI Visuals Marketplace : A marketplace of custom visuals and R-powered visuals

If you wish to learn Power BI, please find the necessary details from below link : https://sqlschool.com/PowerBI-Online-Training.html

This Power BI Online Training includes EVERY detail of each Power BI Visual, Usage and Properties as per the latest versions.

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What is SQL?

SQL stands for Structured Query Language. SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. It is used to perform operations on the data present in database.

SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.

Although most database systems use SQL, most of them also have their own additional proprietary extensions that are usually only used on their system.

However, the standard SQL commands such as “Select”, “Insert”, “Update”, “Delete”, “Create”, and “Drop” can be used to accomplish almost everything that one needs to do with a database.

SQL commands are divided into several different types, among them data manipulation language (DML) and data definition language (DDL) statements, transaction controls and security measures.

Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc.

Opening for Data Analyst Position – PL SQL Experience Mandatory

Company Name: Promocio

Work Location: Begumpet

Designation: Data Analyst

Mandatory Skills Needed: PL SQL & Advanced Excel

Responsibilities: (In Brief)
Data analysis, cleansing & processing data using Advanced Excel and PL SQL
Identify, analyse, and interpret trends or patterns in complex data sets
Combine and collate information from multiple sources and present your findings to the broader group.
Develop and implement databases, data collection systems, data analytics and other strategies that optimize statistical efficiency and quality
Experience of Advance Excel, SQL, is a must.
Knowledge and experience on Google Analytics is a plus.
Strong problem solving ability, should be able to identify key areas of improvements by understanding business process and analyzing data.
Should have eagerness to learn new techniques and methodologies related to Analytics to come up with innovative solutions.
Develop dashboards to track the performance of various campaigns
Dashboard monitoring for day to day business and operational functionalities which enables identifying the risk areas for further mitigation
Update models / reports as and when required

Experience: 1+yrs

Candidate must complete course on SQL and should have working experience on SQL (preferred)

Pls email your updated resume to pavan@promocio.co / 9885737360

You will receive a call if your profile is shortlisted.

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