INF: Error Flushing by Driver Manager

SUMMARY

This article discusses how the Driver Manager calls a driver's SQLError to flush the errors in the driver's error buffer. Chapter 16 of the ODBC SDK "Programmer's Reference" documents the ODBC convention for error text, return codes, and rules for handling error conditions.

Under the Returning Error Messages section in chapter 16, it reads: It is unclear from the last sentence whether the driver clears the current error buffer on entry into the next function, or whether the Driver Manager calls the driver to clear its error buffer before entry into the next function.

This article explains how an application calls ODBC function B() after a previous call to ODBC function A(), the Driver Manager actually calls the driver's SQLError() first and then calls the driver's function B().

Application         Driver Manager                Driver
---------------------------------------------------------------------
A()         ======>    A()           ======>     A() = SQL_ERROR
= SQL_ERROR <======   <======        <======     Returns SQL_ERROR

//Application does not call SQLError()
B()         ======>    B()
                       SQLError()     ======>    SQLError()
                              Loop for clearing errors
                  <=======
                       DM calls Driver’s B()
                       ======>        =======>    B() = SQL_SUCCESS
=SQL_SUCCESS <======   <======        <=======    Returns SQL_SUCCESS