Dal seguente: BUG: The return data type depends on the location of a UNION operation where char and varchar data types are combined in SQL Server 2000
SYMPTOMS
Consider the following scenario. In Microsoft SQL Server 2000, char and varchar data types are combined in a UNION operation. If the UNION operation is included in a view or in a subquery, the return data type of the combined column is char. If the UNION operation is a stand-alone query, the return data type of the combined column is varchar.
WORKAROUND
To work around this problem, manually convert the data types from char to varchar by using the cast function or the convert function.