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 — Obtiene el número de filas afectadas en la última operación MySQL
Descripción
Estilo orientado a objetos
Estilo por procedimientos
Devuelve el numero de filas afectadas por la última consulta INSERT,
UPDATE, REPLACE or
DELETE.
Para instrucciones SELECT mysqli_affected_rows() es equivalente a mysqli_num_rows().
Parámetros
-
link -
Sólo estilo por procediminetos: Un identificador de enlace devuelto por mysqli_connect() o mysqli_init()
Valores devueltos
Un entero mayor que cero indica el número de filas afectadas o recuperadas.
El cero indica que no hay registros en una actualización con una sentencia UPDATE,
que no hay filas que cumplan la cláusula WHERE de la sentencia o
que ninguna consulta ha sido ejecutada todavía. -1 indica que la consulta devolvió
un error.
Nota:
Si el número de filas afectadas es mayor de el máximo valor entero (
PHP_INT_MAX), dicho número será devuelto como una cadena (string).
Ejemplos
Ejemplo #1 Ejemplo de $mysqli->affected_rows
Estilo orientado a objetos
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* Comprueba la conexión */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* Inserta filas */
$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");
/* Actualiza filas */
$mysqli->query("UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Affected rows (UPDATE): %d\n", $mysqli->affected_rows);
/* Elimina filas */
$mysqli->query("DELETE FROM Language WHERE Percentage < 50");
printf("Affected rows (DELETE): %d\n", $mysqli->affected_rows);
/* Selecciona todas las filas */
$result = $mysqli->query("SELECT CountryCode FROM Language");
printf("Affected rows (SELECT): %d\n", $mysqli->affected_rows);
$result->close();
/* Elimina la tabla "Language" */
$mysqli->query("DROP TABLE Language");
/* Cierra la conexión */
$mysqli->close();
?>Estilo por procedimientos
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
if (!$link) {
printf("Can't connect to localhost. Error: %s\n", mysqli_connect_error());
exit();
}
/* Inserta filas */
mysqli_query($link, "CREATE TABLE Language SELECT * from CountryLanguage");
printf("Affected rows (INSERT): %d\n", mysqli_affected_rows($link));
mysqli_query($link, "ALTER TABLE Language ADD Status int default 0");
/* Actualiza filas */
mysqli_query($link, "UPDATE Language SET Status=1 WHERE Percentage > 50");
printf("Affected rows (UPDATE): %d\n", mysqli_affected_rows($link));
/* Elimina filas */
mysqli_query($link, "DELETE FROM Language WHERE Percentage < 50");
printf("Affected rows (DELETE): %d\n", mysqli_affected_rows($link));
/* Selecciona todas las filas */
$result = mysqli_query($link, "SELECT CountryCode FROM Language");
printf("Affected rows (SELECT): %d\n", mysqli_affected_rows($link));
mysqli_free_result($result);
/* Elimina la tabla "Language" */
mysqli_query($link, "DROP TABLE Language");
/* Cierra la conexión */
mysqli_close($link);
?>El resultado de los ejemplos sería:
Affected rows (INSERT): 984 Affected rows (UPDATE): 168 Affected rows (DELETE): 815 Affected rows (SELECT): 169
Ver también
- mysqli_num_rows() - Obtiene el número de filas de un resultado
- mysqli_info() - Obtiene la información de la última consulta ejecutada
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 = $del_stmt->affected_rows;
?>
Otherwise things will just be frustrating ..
Michael ¶
9 years ago
If you need to know specifically whether the WHERE condition of an UPDATE operation failed to match rows, or that simply no rows required updating you need to instead check mysqli::$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 $appointment_date variable. When I run it a second time (making no changes), it returns 0. I also verified the same behavior without using prepared statements.
oilpc at oilpc dot com ¶
14 years ago
For "INSERT" or "UPDATE" statement for modifying data contained in one row of one table I checked if number of affected rows equals 1 to determine success of the operation. It works fine both for errors and false value of WHERE condition (that might be generated according to specific application user acces privileges).
<?php
if ($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";
}
?>
