SQL DQL Commands- Data Query Language

 SQL DQL Commands- Data Query Language

TUTORIAL IN HINDI:

Data Query Language (DQL) contains commands to perform querying and retrieving data from table.

SELECT: This is the same as the projection operation of relational algebra. It is used to select the attribute based on the condition described by WHERE clause.

SYNTAX:

SELECT Column1, Column2, ColumnN

FROM TABLES    

WHERE conditions;  

OR 

SELECT * FROM TABLES 

EXAMPLE:

SELECT Student_Name

FROM Student

WHERE ID > 102;

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SQL:

• The Structured Query Language (SQL) is the language of databases.
• All modern relational databases, including Access, FileMaker Pro, Microsoft SQL Server and Oracle use SQL as their basic building block.
• In fact, it’s often the only way that you can truly interact with the database itself.
• All of the fancy graphical user interfaces that provide data entry and manipulation functionality are nothing more than SQL translators.
• They take the actions you perform graphically and convert them to SQL commands understood by the database.
• SQL is Similar to English
• Fortunately, at its core, SQL is a simple language.
• It has a limited number of commands and those commands are very readable and are almost structured like English sentences.

SQL Commands:

SQL commands are instructions. It is used to communicate with the database. It is also used to perform specific tasks, functions, and queries of data.

Types of SQL Commands:

DDL:

DML:

DQL:

DCL:

TCL:

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