Introduction to 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,

and the class_info table,

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,

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.