Returns a null-terminated string containing the SQLSTATE error
code for the last error. The error code consists of five
characters. '00000' means “no
error.” The values are specified by ANSI SQL and ODBC.
For a list of possible values, see
Appendix B, Error Codes and Messages.
Note that not all MySQL errors are mapped to SQLSTATE error
codes. The value 'HY000' (general error) is
used for unmapped errors.
Return Values
A null-terminated character string containing the SQLSTATE
error code.
