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Using Table Aliases

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:

  • table_name AS table alias
  • table_name table_alias

In the following example, the alias c is assigned to Customer and the alias s is assigned to Store.

USE AdventureWorks;
GO
SELECT c.CustomerID, s.Name
FROM Sales.Customer AS c
JOIN Sales.Store AS s
ON c.CustomerID = s.CustomerID

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 Sales.Customer.CustomerID, /* Illegal reference to Sales.Customer. */
    s.Name
FROM Sales.Customer AS c
JOIN Sales.Store AS s
ON c.CustomerID = s.CustomerID

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