SQL Syntax

SQL Syntax

SQL follows some unique set of rules and guidelines called syntax. Here, we are providing all the basic SQL syntax.

• SQL is not case sensitive. Generally SQL keywords are written in uppercase.
• SQL statements are dependent on text lines. We can place a single SQL statement on one or multiple text lines.
• You can perform most of the action in a database with SQL statements.
• SQL depends on relational algebra and tuple relational calculus.

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SQL statement

SQL statements are started with any of the SQL commands/keywords like SELECT, INSERT, UPDATE, DELETE, ALTER, DROP etc. and the statement ends with a semicolon (;).

Example of SQL statement:

1. SELECT "column_name" FROM "table_name";  

Why semicolon is used after SQL statements:

Semicolon is used to separate SQL statements. It is a standard way to separate SQL statements in a database system in which more than one SQL statements are used in the same call.

In this tutorial, we will use semicolon at the end of each SQL statement.

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SQL Commands

These are the some important SQL command:

SELECT: it extracts data from a database.

UPDATE: it updates data in database.

DELETE: it deletes data from database.

CREATE TABLE: it creates a new table.

ALTER TABLE: it is used to modify the table.

DROP TABLE: it deletes a table.

CREATE DATABASE: it creates a new database.

ALTER DATABASE: It is used to modify a database.

INSERT INTO: it inserts new data into a database.

CREATE INDEX: it is used to create an index (search key).

DROP INDEX: it deletes an index.