Not consisent result about mysql_stmt_execute and mysql_stmt_errno.

[hello okay]

Mysql version: 8.0.18

What's the reason of the result of mysql_stmt_execute not equal zero, but mysql_stmt_errno return zero?

According to doc, https://dev.mysql.com/doc/c-api/8.0/en/mysql-stmt-errno.html,
An error code value. Zero if no error occurred.

If result of mysql_stmt_execute not equal zero, it means fail to call mysql_stmt_execute, but mysql_stmt_errno return zero, this conflicts.