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
mysqli::$affected_rows
mysqli_affected_rows
(PHP 5, PHP 7, PHP 8)
mysqli::$affected_rows -- mysqli_affected_rows — Retourne le nombre de lignes affectées par la dernière opération MySQL
Description
Style orienté objet
Style procédural
Retourne le nombre de lignes affectées par la dernière requête
INSERT, UPDATE,
REPLACE ou DELETE
associée au paramètre link.
Fonctionne comme mysqli_num_rows() pour les requêtes
SELECT.
Liste de paramètres
-
mysql -
Seulement en style procédural : Un objet mysqli retourné par la fonction mysqli_connect() ou mysqli_init().
Valeurs de retour
Un entier plus grand que zéro indique le nombre de lignes affectées ou recherchées.
Zéro indique qu'aucun enregistrement n'a été modifié par une requête du type
UPDATE, aucune ligne ne correspond à la clause
WHERE dans la requête ou bien qu'aucune requête
n'a été exécutée. -1 indique que la requête a retourné
une erreur ou que mysqli_affected_rows() a été appelé sur
une requête SELECT non-tampon.
Note:
Si le nombre de lignes affectées est plus grand que la valeur maximale (
PHP_INT_MAX) que peut prendre un entier, le nombre de lignes affectées sera retourné en tant que chaîne de caractères.
Exemples
Exemple #1 Exemple avec $mysqli->affected_rows
Style orienté objet
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* Insertion d'une ligne */
$mysqli->query("CREATE TABLE Language SELECT * from CountryLanguage");
printf("Nombre de lignes affectées (INSERT): %d\n", $mysqli->affected_rows);
$mysqli->query("ALTER TABLE Language ADD Status int default 0");
/* Modification d'une ligne */
$mysqli->query("UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Nombre de lignes affectées (UPDATE): %d\n", $mysqli->affected_rows);
/* Effacement d'une ligne */
$mysqli->query("DELETE FROM Language WHERE Percentage < 50");
printf("Nombre de lignes affectées (DELETE): %d\n", $mysqli->affected_rows);
/* Sélection de toutes les lignes */
$result = $mysqli->query("SELECT CountryCode FROM Language");
printf("Nombre de lignes affectées (SELECT): %d\n", $mysqli->affected_rows);
/* Delete table Language */
$mysqli->query("DROP TABLE Language");
?>Style procédural
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* Insertion d'une ligne */
mysqli_query($link, "CREATE TABLE Language SELECT * from CountryLanguage");
printf("Nombre de lignes affectées (INSERT): %d\n", mysqli_affected_rows($link));
mysqli_query($link, "ALTER TABLE Language ADD Status int default 0");
/* Modification d'une ligne */
mysqli_query($link, "UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Nombre de lignes affectées (UPDATE): %d\n", mysqli_affected_rows($link));
/* Effacement d'une ligne */
mysqli_query($link, "DELETE FROM Language WHERE Percentage < 50");
printf("Nombre de lignes affectées (DELETE): %d\n", mysqli_affected_rows($link));
/* Selection de toutes les lignes */
$result = mysqli_query($link, "SELECT CountryCode FROM Language");
printf("Nombre de lignes affectées (SELECT): %d\n", mysqli_affected_rows($link));
/* Effacement de la table "language" */
mysqli_query($link, "DROP TABLE Language");
?>Les exemples ci-dessus vont afficher :
Nombre de lignes affectées (INSERT): 984 Nombre de lignes affectées (UPDATE): 168 Nombre de lignes affectées (DELETE): 815 Nombre de lignes affectées (SELECT): 169
Voir aussi
- mysqli_num_rows() - Retourne le nombre de lignes dans le jeu de résultats
- mysqli_info() - Retourne des informations à propos de la dernière requête exécutée
add a note
User Contributed Notes 7 notes
Anonymous ¶
13 years ago
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 = $del_stmt->affected_rows;
?>
Otherwise things will just be frustrating ..
Michael ¶
10 years ago
If you need to know specifically whether the WHERE condition of an UPDATE operation failed to match rows, or that simply no rows required updating you need to instead check mysqli::$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
)
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();
$db->affected_rows;
I found this useful to double check things in an SQL prompt, to make sure affected_rows is reflecting what I expect (changed rows as opposed to matched rows in an update statement), which indeed it did.
1. https://github.com/php/php-src/blob/1521cafee29e23ca147ec777f3770a7ac46c6880/ext/mysqli/mysqli_api.c#L36-L49
2. https://mariadb.com/kb/en/row_count/
fastest963 at gmail dot com ¶
10 years ago
empty($db->affected_rows) will return TRUE even if affected_rows is greater than 0. Manually check < 1 if you're looking for failure.
anonymous ¶
8 years ago
This may seem obvious, but if you do an UPDATE with each of the values in your SET clause having the exact same value that is already in the table, then affected_rows returns 0. For example:
<?php
$mysqli = new mysqli($host, $usr, $pwd, $db, $port);
$appointment_date = "2015-12-07";
$sql = "update appointments set appointment_date = ? where appointment_id = 78";
$stmt = $mysqli->prepare($sql);
$stmt->bind_param("s",$appointment_date);
$stmt->execute();
echo $mysqli ->affected_rows . "<br>";
?>
This returns 1 the first time I run it after changing the value of the $appointment_date variable. When I run it a second time (making no changes), it returns 0. I also verified the same behavior without using prepared statements.
oilpc at oilpc dot com ¶
15 years ago
For "INSERT" or "UPDATE" statement for modifying data contained in one row of one table I checked if number of affected rows equals 1 to determine success of the operation. It works fine both for errors and false value of WHERE condition (that might be generated according to specific application user acces privileges).
<?php
if ($mysqli->affected_rows==1){
echo "success";
}
else {
echo "fail";
}
?>
Checking if mysqli->affected_rows will equal -1 or not is not a good method of determining success of "INSERT IGNORE" statements. Example: Ignoring duplicate key errors while inserting some rows containing data provided by user only if they will match specified unique constraint causes returning of -1 value by mysqli->affected_rows even if rows were inserted. (checked on MySQL 5.0.85 linux and php 5.2.9-2 windows). However mysqli->sqlstate returns no error if statement was executed successfully.
<?php
if ($mysqli->affected_rows!=-1){
echo "success";// for "INSERT IGNORE" statements will not occur if there were any duplicate key errors ignored during execution of the query
}
else {
echo "fail";// "INSERT IGNORE" statements causing any duplicate key errors (however ignored) lead to mysqli->affected_rows equal -1
}
// Example below works for "INSERT IGNORE" stattements, too
if ($mysqli->sqlstate=="00000"){
echo "success";
}
else {
echo "fail";
}
?>
