Sams Teach Yourself MySQL in 21 Days, Second Edition

Handling Errors

We're nearly ready to put our program together! There's just one more important thing to include: error handling.

Nearly all the API's functions return a value indicating success or failure. If a function fails, you can use mysql_error() and mysql_errno() to report on what went wrong.

For example, we will test the result of mysql_real_connect(). As you saw just now, it returns a MYSQL* connection handle if the connection attempt succeeds, or NULL if it fails. Let's add some error handling to our connection routine, which should now look like this:

 if (mysql_real_connect ( mysql, db_host, db_user, db_pass, db_name, db_port, unix_socket, db_flags) == NULL ) { fprintf (stderr, "mysql_real_connect() failed!\nError %u: %s\n", mysql_errno ...