PDOStatement::rowCount

说明

PDOStatement::rowCount() returns the number of rows affected by the last DELETE, INSERT, or UPDATE statement executed by the corresponding PDOStatement object.

If the last SQL statement executed by the associated PDOStatement was a SELECT statement, some databases may return the number of rows returned by that statement. However, this behaviour is not guaranteed for all databases and should not be relied on for portable applications.

例

例子 1. Return the number of deleted rows PDOStatement::rowCount() returns the number of rows affected by a DELETE, INSERT, or UPDATE statement. <?php /* Delete all rows from the FRUIT table */ $del = $dbh->prepare('DELETE FROM fruit'); $del->execute(); /* Return number of rows that were deleted */ print("Return number of rows that were deleted:\n"); $count = $del->rowCount(); print("Deleted $count rows.\n"); ?> 上例将输出： Deleted 9 rows.

例子 2. Counting rows returned by a SELECT statement For most databases, PDOStatement::rowCount() does not return the number of rows affected by a SELECT statement. Instead, use PDO::query() to issue a SELECT COUNT(*) statement with the same predicates as your intended SELECT statement, then use PDOStatement::fetchColumn() to retrieve the number of rows that will be returned. Your application can then perform the correct action. <?php $sql = "SELECT COUNT(*) FROM fruit WHERE calories > 100"; if ($res = $conn->query($sql)) {     // Check the number of rows that match the SELECT statement     if ($res->fetchColumn() > 0) {         // Issue the real SELECT statement and work with the results          $sql = "SELECT name FROM fruit WHERE calories > 100";          foreach ($conn->query($sql) as $row) {              print "Name: " .  $row['NAME'] . "\n";          }     }     // No rows matched -- do something else     else {         print "No rows matched the query.";     } } $res = null; $conn = null; ?> 上例将输出： apple banana orange pear

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