PDO were rows affected during execute statement - php

Question

I have found many ways to use the exec statement for PDO, but I'm not sure it helps me. My understanding is that I have to use the execute() function for prepared statements. I am updating a row with data from user input, so I would like to use a prepared statement instead of the query() call.
My code is as follows:
$dbh = buildDBConnector();
$sql = "UPDATE tb_users
SET authState=1
WHERE id = ? AND authPass = ?";
$q = $dbh->prepare($sql);
$f = $q->execute(array($id,$authPass));
if($f){
echo '<br />Success<br />';
}else{
echo '<br />Failure<br />';
}
The issue is that the query itself is error free and executes fine, so there is no failure to store in $f. However, I need to know if it actually found the row to update, then successfully updated it. In other words, I need the affected rows. When googling and such, it keeps coming to the exec statement, but from my understanding, exec isn't for prepared statements? Any suggestions?

Answer 1

Try $q->rowCount(). Prepared statements will return the number of affected rows via that method.

Answer 2

A side note: when updating a table with identical values rowCount() will return always 0. This is normal behavior. You can change it yourself since PHP 5.3 by creating a PDO object with following attribute:
<? php
$p = new PDO($dsn, $user, $pass, array(PDO::MYSQL_ATTR_FOUND_ROWS => true));
?>
The rowCount() then will return how many rows your update-query actually found/matched.

Answer 3

$q->rowCount() returns the number of rows affected by the last (executed) SQL statement where $q is the prepared statement which is often called $stmt.
So most users who read this might want something like:
$pdo = new PDO($dsn, $username, $password);
$sql = "UPDATE tb_users SET authState=1 WHERE id = ? AND authPass = ?";
$stmt = $pdo->prepare($sql);
$stmt->execute(array($id, $authPass));
if ($stmt->rowCount()){
echo 'Success: At least 1 row was affected.';
} else{
echo 'Failure: 0 rows were affected.';
}

Answer 4

PDO's rowCount() from prepared statements returns affected rows if it's an UPDATE, DELETE or INSERT statement. Otherwise it returns how many rows are returned from SELECT statement.

Answer 5

para evitar que la actualización retorne 0, deberás añadir algo al final de la cadena de conexión.
Conexion.php
<?php $cadena = "$manejador:host=$servidor;dbname=$dbname";
$cnx = new PDO($cadena, $usuario, $pass, array(PDO::MYSQL_ATTR_FOUND_ROWS => true));
?>
clase.php
<?php
...
global $cnx;
$pre = $cnx->prepare($sql);
$pre->execute($parametros);
$rpta = $pre->rowCount();
return $rpta;
?>

Answer 6

i think PDO rowCount() is useless in MySQL with single UPDATE query. because it always return 0;
ex:
TABLE{id=1, col1="A"}
UPDATE TABLE SET col1="AA" WHERE id=1;
rowCount will return 0;
also
UPDATE TABLE SET col1="AA" WHERE id=999;
rowCount will return 0;
so rowCount() is useless in this case.
i have not tested yet with this query UPDATE TABLE SET col1="AA"