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SQL Syntax

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SQL is not syntax strict like JavaScript which mean to say that in SQL uppercases and lowercases don’t matter as long as you have spelled them correctly.

For example:

“select * from users” AND “SELECT * FROM users” is the same

SQL queries can be ended with a semicolon or can be simply ignored, however there are some DBMS which require that the query must be ended with a semicolon, else they won’t execute the query.

SQL Queries can be nested in other SQL queries for performing complex operations in a single go.

SQL queries can be written in single line as well as can be broken to multiline for better readability.

For example:

“Select * from users where lastname=’Smith’”

This query can be written as multiline

“Select * From Users Where lastname=’smith’”

This increases the readability.

Syntax for SQL queries must be followed correctly and cannot written out of order i.e. “select * from users” cannot be written as “select from * users”

Simple/most commonly used SQL commands

Select – this SQL statements allow us to retrieve data from the database, based upon our conditions we specify.
Insert – this SQL statement allows us to insert data to some specific table in the database.
Update – this SQL statement is used to modify or update the existing record based on the condition we specify.
Delete – this SQL statement will delete a data record from the table we mention.

Extended SQL Operations

Create Database – to create a completely new database with SQL without having to create the database from the dbms itself.
Alter Database – to modify the database structure, like adding a new table or removing tables.
Create Table – this command is used to create a new table in the database selected.
Alter table – modifies the table structure.
Drop table – simply deletes all the data records and the table itself from the database.
Create index – this command is used to create a search index on some specific column of the table.
Drop index – removes the search key from the column of the table.

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