SQL Alias - AS Keyword

Alias is used to give an alias name to a table or a column, which can be a resultset table too. This is quite useful in case of large or complex queries. Alias is mainly used for giving a short alias name for a column or a table with complex names.

Syntax of Alias for table names,

SELECT column-name FROM table-name AS alias-name

Following is an SQL query using alias,

SELECT * FROM Employee_detail AS ed;

Syntax for defining alias for columns will be like,

SELECT column-name AS alias-name FROM table-name;

Example using alias for columns,

SELECT customer_id AS cid FROM Emp;

Example of Alias in SQL Query

Consider the following two tables,

The class table,

IDName
1abhi
2adam
3alex
4anu
5ashish

and the class_info table,

IDAddress
1DELHI
2MUMBAI
3CHENNAI
7NOIDA
8PANIPAT

Below is the Query to fetch data from both the tables using SQL Alias,

SELECT C.id, C.Name, Ci.Address from Class AS C, Class_info AS Ci where C.id = Ci.id;

and the resultset table will look like,

IDNameAddress
1abhiDELHI
2adamMUMBAI
3alexCHENNAI

SQL Alias seems to be quite a simple feature of SQL, but it is highly useful when you are working with more than 3 tables and have to use JOIN on them.