invalid table alias

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.BusinessEntityID ;

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:

就是说如果将表命名了别名，整个程序都要使用该别名。