MySQL 8.0 C API Developer Guide
int mysql_reload(MYSQL *mysql)
Asks the MySQL server to reload the grant tables. The
connected user must have the
RELOAD privilege.
This function is deprecated. Use
mysql_real_query() or
mysql_query() to issue an SQL
FLUSH PRIVILEGES statement
instead.
Commands were executed in an improper order.
The MySQL server has gone away.
The connection to the server was lost during the query.
An unknown error occurred.