A very popular MySQL idiom is to use the return value of %mysql_num_rows()% to reflect the number of rows that will be returned by the last SELECT statement that was issued. But in most database APIs, the number of rows *affected* by executing a SELECT statement is zero -- and that's what %xx_num_rows()% will return. If your database supports scrollable cursors, and you request a scrollable cursor when you issue your SELECT statement, you *will* get an accurate count of the number of rows in the result set. Most times, however, you can either issue a separate SELECT COUNT(*) if you actually want the number of rows, or just try fetching the first row from the result set. For small result sets, you can use %PDO::fetchAll()% to return all of the rows in the result set. The %ibm_db2% extension that Apache Derby requires will probably implement a %db2_fetch_all()% function in the near future to provide the equivalent functionality. You can also step through the results of a forward-only cursor until the fetch call fails and increment a counter to find out how many rows are in the result set.