mysqli::$affected_rows

mysqli_affected_rows

(PHP 5, PHP 7, PHP 8)

mysqli::$affected_rows -- mysqli_affected_rows — 直前の MySQL の操作で変更された行の数を得る

説明

オブジェクト指向型

int|string $mysqli->affected_rows;

手続き型

mysqli_affected_rows(mysqli $mysql): int|string

直近の INSERT、 UPDATE、REPLACE あるいは DELETE クエリにより変更された行の数を返します。

SELECT 文の場合は、 mysqli_num_rows() と同じように動作します。

パラメータ

link: 手続き型のみ: mysqli_connect() あるいは mysqli_init() が返す mysqliオブジェクト。

戻り値

正の整数が返された場合、それは変更された行数かあるいは取得された行数を示します。ゼロが返された場合、それは UPDATE 文でレコードが更新されなかったか WHERE 条件に当てはまる行がなかった、またはクエリが実行されなかったことを示します。-1 は、クエリがエラーを返したか、 mysqli_affected_rows() がバッファリングされていない SELECT に対してコールされたことを示します。

注意:
変更された行数が整数型の最大値 (PHP_INT_MAX) をこえた場合、結果の行数は文字列として返されます。

例

例1 $mysqli->affected_rows の例

オブジェクト指向型

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* 行を挿入します */
$mysqli->query("CREATE TABLE Language SELECT * from CountryLanguage");
printf("Affected rows (INSERT): %d\n", $mysqli->affected_rows);

$mysqli->query("ALTER TABLE Language ADD Status int default 0");

/* 行を更新します */
$mysqli->query("UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Affected rows (UPDATE): %d\n", $mysqli->affected_rows);

/* 行を削除します */
$mysqli->query("DELETE FROM Language WHERE Percentage < 50");
printf("Affected rows (DELETE): %d\n", $mysqli->affected_rows);

/* 全件選択します。 */
$result = $mysqli->query("SELECT CountryCode FROM Language");
printf("Affected rows (SELECT): %d\n", $mysqli->affected_rows);

/* Language テーブルを削除します。 */
$mysqli->query("DROP TABLE Language");

手続き型

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "world");

/* 行を挿入します */
mysqli_query($link, "CREATE TABLE Language SELECT * from CountryLanguage");
printf("Affected rows (INSERT): %d\n", mysqli_affected_rows($link));

mysqli_query($link, "ALTER TABLE Language ADD Status int default 0");

/* 行を更新します */
mysqli_query($link, "UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Affected rows (UPDATE): %d\n", mysqli_affected_rows($link));

/* 行を削除します */
mysqli_query($link, "DELETE FROM Language WHERE Percentage < 50");
printf("Affected rows (DELETE): %d\n", mysqli_affected_rows($link));

/* 全件選択します。 */
$result = mysqli_query($link, "SELECT CountryCode FROM Language");
printf("Affected rows (SELECT): %d\n", mysqli_affected_rows($link));

/* Language テーブルを削除します。 */
mysqli_query($link, "DROP TABLE Language");

上の例の出力は以下となります。

Affected rows (INSERT): 984
Affected rows (UPDATE): 168
Affected rows (DELETE): 815
Affected rows (SELECT): 169

参考

mysqli_num_rows() - 結果セットの行数を取得する
mysqli_info() - 直近に実行されたクエリの情報を取得する

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User Contributed Notes 5 notes

down

Anonymous ¶

13 years ago

On "INSERT INTO ON DUPLICATE KEY UPDATE" queries, though one may expect affected_rows to return only 0 or 1 per row on successful queries, it may in fact return 2.

From Mysql manual: "With ON DUPLICATE KEY UPDATE, the affected-rows value per row is 1 if the row is inserted as a new row and 2 if an existing row is updated."

See: http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html

Here's the sum breakdown _per row_:
+0: a row wasn't updated or inserted (likely because the row already existed, but no field values were actually changed during the UPDATE)
+1: a row was inserted
+2: a row was updated

down

Jacques Amar ¶

7 years ago

While using prepared statements, even if there is no result set (Like in an UPDATE or DELETE), you still need to store the results before affected_rows returns the actual number:

<?php
$del_stmt->execute();
$del_stmt->store_result();
$count = $del_stmt->affected_rows;
?>

Otherwise things will just be frustrating ..

down

Michael ¶

10 years ago

If you need to know specifically whether the WHERE condition of an UPDATE operation failed to match rows, or that simply no rows required updating you need to instead check mysqli::$info.

As this returns a string that requires parsing, you can use the following to convert the results into an associative array.

Object oriented style:

<?php
    preg_match_all ('/(\S[^:]+): (\d+)/', $mysqli->info, $matches); 
    $info = array_combine ($matches[1], $matches[2]);
?>

Procedural style:

<?php
    preg_match_all ('/(\S[^:]+): (\d+)/', mysqli_info ($link), $matches); 
    $info = array_combine ($matches[1], $matches[2]);
?>

You can then use the array to test for the different conditions

<?php
    if ($info ['Rows matched'] == 0) {
        echo "This operation did not match any rows.\n";
    } elseif ($info ['Changed'] == 0) {
        echo "This operation matched rows, but none required updating.\n";
    }

    if ($info ['Changed'] < $info ['Rows matched']) {
        echo ($info ['Rows matched'] - $info ['Changed'])." rows matched but were not changed.\n";
    }
?>

This approach can be used with any query that mysqli::$info supports (INSERT INTO, LOAD DATA, ALTER TABLE, and UPDATE), for other any queries it returns an empty array.

For any UPDATE operation the array returned will have the following elements:

Array
(
    [Rows matched] => 1
    [Changed] => 0
    [Warnings] => 0
)

down

mishell dot mercer at gmail dot com ¶

3 months ago

Do note that if you have turned off autocommit, and plan to do multiple actions before the commit, $affected_rows only works per statement. This means if, for example, you want to run multiple INSERT statements and tally all rows inserted after they are commited, a running counter will need to be implemented.

// start the count
$count = 0;

// turn off autocommit
$mysqli->autocommit(FALSE);
$mysqli->begin_transaction;

// insert a couple items
$query = "
    INSERT INTO users ('id','username','email') 
    VALUES (1, 'userguy', 'userguy@mail.com'), (2, 'some_user', 'some_user@ymail.com')
";
$mysqli->query($query);
echo $mysqli->affected_rows;  // 2 - correct
$count += $mysqli->affected_rows;  // add to the count

// insert one more
$query = "
    INSERT INTO users ('id','username','email') 
    VALUES (3, 'anotherone', 'anotherone@mail.com')
";
$mysqli->query($query);
$count += $mysqli->affected_rows;

// insert one more
$query = "
    INSERT INTO users ('id','username','email') 
    VALUES (4, 'thefourth', 'thefourth@gmail.com')
";
$mysqli->query($query);
$count += $mysqli->affected_rows;

// commit these statements to the database
$mysqli->commit();

echo $mysqli->affected_rows;  // 1 - only counts the last statement run
echo "Actual count: ".$count;  // 4

down

-3

lucgommans.nl ¶

1 year ago

Under the hood, this calls into mysql_affected_rows (1). The MariaDB function ROW_COUNT() mentions (2) that it is the equivalent of that C API function. These two lines, SQL followed by PHP, should be equivalent:

SELECT ROW_COUNT();
$db->affected_rows;

I found this useful to double check things in an SQL prompt, to make sure affected_rows is reflecting what I expect (changed rows as opposed to matched rows in an update statement), which indeed it did.

1. https://github.com/php/php-src/blob/1521cafee29e23ca147ec777f3770a7ac46c6880/ext/mysqli/mysqli_api.c#L36-L49
2. https://mariadb.com/kb/en/row_count/

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