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Thursday, September 14, 2006

why System.InvalidCastException comes whild calling OdbcConnection.GetSchema

 A System.InvalidCastException exception may occur when you call the OdbcConnection.GetSchema method in the .NET Framework 2.0

CAUSE

The OdbcConnection.GetSchema method calls the SQLGetTypeInfo function in the ODBC API. The SQLGetTypeInfo function returns a result set that contains several columns. Some ODBC drivers may implement a column by using an incorrect SQL data type. For example, some ODBC drivers implement the following columns by using a signed value:
CASE_SENSITIVE
FIXED_PREC_SCALE
UNSIGNED_ATTRIBUTE
These columns should use the SQL_SMALLINT value instead. The SQL_SMALLINT value is an unsigned value. If one of these columns uses a signed value, a System.InvalidCastException exception occurs when Microsoft ADO.NET tries to cast the value to a System.Int32 value.
 

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