const char * mysql_sqlstate(MYSQL * mysql);
Returns a string containing the SQLSTATE error code for the most recently invoked function that can succeed or fail. The error code consists of five characters. '00000' means no error. The values are specified by ANSI SQL and ODBC
Please note that not all client library error codes are mapped to SQLSTATE errors. Errors which can't be mapped will returned as value HY000.