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,
| ID | Name |
|---|
| 1 | abhi |
| 2 | adam |
| 3 | alex |
| 4 | anu |
| 5 | ashish |
and the class_info table,
| ID | Address |
|---|
| 1 | DELHI |
| 2 | MUMBAI |
| 3 | CHENNAI |
| 7 | NOIDA |
| 8 | PANIPAT |
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,
| ID | Name | Address |
|---|
| 1 | abhi | DELHI |
| 2 | adam | MUMBAI |
| 3 | alex | CHENNAI |
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.
