The readability of a SELECT statement can be improved by giving a table an alias, also known as a correlation name or range variable. A table alias can be assigned either with or without the AS keyword:
In this example, the alias p is assigned to publishers.
USE pubs
SELECT p.pub_id, p.pub_name
FROM publishers AS p
If an alias is assigned to a table, all explicit references to the table in the Transact-SQL statement must use the alias, not the table name. For example, the following SELECT generates a syntax error because it uses the name of the table when an alias has been assigned:
SELECT Customers.CustomerID, /* Illegal reference to Customers. */
Cst.FirstName, Cst.LastName
FROM Northwind.dbo.Customers AS Cst
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