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# PDOStatement::rowCount

(no version information, might be only in CVS)

PDOStatement::rowCount -- Returns the number of rows affected by the last SQL statement

## 说明

int PDOStatement::rowCount ( void )

警告
本函数是实验性的。本函数的行为，包括函数名称以及其它任何关于本函数的文档可能会在没有通知的情况下随 PHP 以后的发布而改变。使用本函数风险自担。

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::fetchSingle() 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->fetchSingle() > 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

## 参见

PDOStatement::columnCount()
PDOStatement::query()
PDOStatement::fetchSingle()

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