Datatype conversion for transfer processing

Datatype conversion is handled differently by the access service for the transfer types.

Bulk copy and express transfer processing

After converting the incoming source database datatypes, the source datatypes are converted into the actual datatypes of the target columns. If the source and target columns have incompatible datatypes, the transfer ends with an error.

Destination-template transfer processing

After converting the incoming source database datatypes, the datatype qualifiers specified are used, with the question marks in the template. When the question marks do not have qualifiers, the access service uses the datatypes of the source to determine the default qualifiers.

WARNING! ECDA Option for ODBC cannot correctly transfer varchar values containing empty strings (zero length non-null strings), in the bulk copy and destination-template transfer process. Empty string varchar values are interpreted as NULL values. However, express transfer processes this empty string correctly.