How to use AS Keyword in Sql

The keyword AS is used to assign an alias to the column or a table.

Syntax:

Basic syntax of table alias is below

SELECT column1, column2.... FROM your_table_name AS alias_name WHERE [condition];

Basic syntax of column alias is below

SELECT column_name AS alias_name FROM your_table_name WHERE [condition];

Example:

Following are two tables first is “Employee” table and second is “Salary” table.

EMPLOYEE table

Id	Name	Age	Address	Department	Gender
1	Alok Kumar Singh	30	IN	IT	Male
2	Tomas Paul	45	NZ	IT	Male
3	Cristomfer Dee	85	AU	HR	Female
4	Niel Macengi	55	US	BPO	Female

SALARY table

ID	EmployeeId	Amount	Date
1	1	50000	12-05-2016
2	2	54000	12-05-2016
3	3	456463	12-05-2016
4	4	150021	12-05-2016
5	1	450000	12-06-2016

Following is the example of table alias

USE SQLCLR

GO

SELECT Emp.Id , Emp.Name, Sal.Amount, Sal.Date FROM EMPLOYEE AS Emp

,Salary Sal WHERE Emp.Id=Sal.EmployeeId ORDER BY Emp.Id

GO

                                             or

USE SQLCLR

GO

SELECT Emp.Id , Emp.Name, Sal.Amount, Sal.Date FROM EMPLOYEE AS Emp

INNER JOIN Salary Sal ON Emp.Id=Sal.EmployeeId ORDER BY Emp.Id

GO

Id	Name	Amount	Date
1	Alok Kumar Singh	50000	12-05-2016
1	Alok Kumar Singh	450000	12-06-2016
2	Tomas Paul	54000	12-05-2016
3	Cristomfer Dee	456463	12-05-2016
4	Niel Macengi	150021	12-05-2016

Following is the usage of column alias

USE SQLCLR

  GO

  SELECT Id AS EmployeeID, Name AS EmployeeName FROM EMPLOYEE

  GO

EmployeeID	EmployeeName
1	Alok Kumar Singh
2	Tomas Paul
3	Cristomfer Dee
4	Niel Macengi