[C++][FlightSQL][ODBC][SQLBindCol] support returning values for indicator pointer with null data pointer #47021

Describe the enhancement requested

Current behavior: Flight SQL ODBC doesn't return data length inside indicator pointer if data pointer is null when SQLBindCol is called.

If TargetValuePtr is a null pointer, the driver unbinds the data buffer for the column. An application can unbind all columns by calling SQLFreeStmt with the SQL_UNBIND option. An application can unbind the data buffer for a column but still have a length/indicator buffer bound for the column, if the TargetValuePtr argument in the call to SQLBindCol is a null pointer but the StrLen_or_IndPtr argument is a valid value.

AC:

• support returning values for indicator pointer with null data pointer.

• Parent issue: [C++] Implement ODBC driver "wrapper" using FlightSQL #30622

Component(s)

C++, FlightRPC