MySQL 8.0 C API Developer Guide
bool mysql_more_results(MYSQL *mysql)
This function is used when you execute multiple statements
specified as a single statement string, or when you execute
CALL
statements, which can
return multiple result sets.
mysql_more_results()
true if
more results exist from the currently executed statement, in
which case the application must call
mysql_next_result()
to fetch
the results.
TRUE
(1) if more results exist.
FALSE
(0) if no more results exist.
In most cases, you can call
mysql_next_result()
instead to
test whether more results exist and initiate retrieval if so.
See Chapter 23, C API Multiple Statement Execution Support, and Section 7.48, “mysql_next_result()”.