Описание
int
db2_num_rows ( resource stmt )
Returns the number of rows deleted, inserted, or updated by an SQL
statement.
To determine the number of rows that will be returned by a SELECT
statement, issue SELECT COUNT(*) with the same predicates as your
intended SELECT statement and retrieve the value.
If your application logic checks the number of rows returned by a SELECT
statement and branches if the number of rows is 0, consider modifying your
application to attempt to return the first row with one of
db2_fetch_assoc(), db2_fetch_both(),
db2_fetch_array(), or db2_fetch_row(),
and branch if the fetch function returns FALSE.
Замечание:
If you issue a SELECT statement using a scrollable cursor,
db2_num_rows() returns the number of rows returned by
the SELECT statement. However, the overhead associated with scrollable
cursors significantly degrades the performance of your application, so if
this is the only reason you are considering using scrollable cursors,
you should use a forward-only cursor and either call SELECT COUNT(*) or
rely on the boolean return value of the fetch functions to
achieve the equivalent functionality with much better performance.