Using Aliases in SQL Server

You can use some alias for table in the select query for better readability of the query, Aliases of the table are very useful when you are using complex query with multiple lines. Aliases of the tables in the Sql server are also called as a correlation name or range variable.
You can use table alias with or without the AS keyword like the following:

table_name AS table alias
table_name table_alias

Suppose you have a query like this:

SELECT tbl_employee.ID, tbl_employee.Name, tbl_details.Age
 FROM tbl_employee JOIN tbl_details ON (tbl_employee.ID = tbl_details.ID

And Now in the following example, the alias a is assigned to tbl_employee and the alias b is assigned to tbl_details.

SELECT a.ID, a.Name, b.Age
 FROM tbl_employee AS a JOIN tbl_details AS b ON (a.ID = b.ID)