MySQL 5.6 C API Developer Guide
my_ulonglong 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()
.