mysql_error - returns the last error message for the most recent
    function call
  
  - 
    #include <mysql.h>
const char * mysql_error(MYSQL * mysql);
    
Returns the last error message for the most recent function call
    that can succeed or fail. An empty string means no error occurred.
  - •
- mysql is a connection identifier, which was
      previously allocated by mysql_init(3) and connected by
      mysql_real_connect(3).
  - •
- Client error codes are listed in errmsg.h header
      file, server error codes are listed in
      mysqld_error.h header file of the server source
      distribution.
- •
- Client error messages can be obtained by calling
      mariadb_get_infov(3) and passing the parameter
      MARIADB_CLIENT_ERRORS
  - •
- mysql_errno(3)
- •
- mysql_sqlstate(3)