Description
SQL Aliases are used to give a temporary and customize and more readable name of a database column while retrieving value with a select query. Alias can also be given to a table. It will help to shorten the table name while performing join on a table.
Syntax
The Alias syntax for a column is as follows:
Select column_name AS alias_name from table_name;
Column name => The operations that can be performed on a column in the table.
Examples
The below example describes the alias commands with the help of join in sql database.
[c]
sql> select * from employee;
+--------+--------+---------+
| emp_id | ename | dept_no |
+--------+--------+---------+
| 1001 | jack | 10 |
| 1002 | maddi | 20 |
| 1003 | maddie | 10 |
| 1004 | max | 20 |
| 1004 | capi | 30 |
+--------+--------+---------+
5 rows in set (0.00 sec)
sql> select * from department;
+---------+--------------+----------+
| dept_no | dept_name | city |
+---------+--------------+----------+
| 10 | finance | texas |
| 20 | capital | new york |
| 30 | manager | ausralia |
| 40 | applications | usa |
| 50 | technology | canada |
+---------+--------------+----------+
5 rows in set (0.00 sec)
sql> select employee.emp_id,employee.ename,department.dept_name,department.city from department right join employee on department.dept_no=employee.dept_no;
+--------+--------+-----------+----------+
| emp_id | ename | dept_name | city |
+--------+--------+-----------+----------+
| 1001 | jack | finance | texas |
| 1003 | maddie | finance | texas |
| 1002 | maddi | capital | new york |
| 1004 | max | capital | new york |
| 1004 | capi | manager | ausralia |
+--------+--------+-----------+----------+
5 rows in set (0.00 sec)
[/c]
Here in the above example the table alias is used to in the query and performed right join on both employee and department table.
Key Points
- SQL Aliases - Used to give a temporary and customize and more readable name of a database column.