uint64_t
mysql_stmt_num_rows(MYSQL_STMT *stmt)
Returns the number of rows in the result set.
The use of
mysql_stmt_num_rows() depends
on whether you used
mysql_stmt_store_result() to
buffer the entire result set in the statement handler. If you
use mysql_stmt_store_result(),
mysql_stmt_num_rows() may be
called immediately. Otherwise, the row count is unavailable
unless you count the rows as you fetch them.
mysql_stmt_num_rows() is
intended for use with statements that return a result set,
such as SELECT. For statements
such as INSERT,
UPDATE, or
DELETE, the number of affected
rows can be obtained with
mysql_stmt_affected_rows().