Correct way to write PDO update statements

问题

Is this the correct way to write a PDO update statement? I based it off a tutorial I saw online but it doesn't seem to be doing anything at all when fired by AJAX (even though the AJAX request is being logged as successful in the console, no update is made to the database):

$duedate = $_POST["duedate"];
$status = $_POST["status"];
$id = $_POST["id"];

$sql = "UPDATE pm_schedule SET duedate=?, status=? WHERE id=?";
$q = $pdo->prepare($sql);
$q->execute(array($duedate,$status,$id));

回答1:

Yes, it's correct, but you need to tell PDO to raise an error on error.
So, make your connection code like this:

$dsn = "mysql:host=$host;dbname=$db;charset=utf8";
$opt = array(
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
);
$pdo = new PDO($dsn, $user, $pass, $opt);

And make sure you can see PHP errors. So, you'll kn ow what's going wrong.

回答2:

$duedate = $_POST["duedate"];
$status = $_POST["status"];
$id = $_POST["id"];

try {
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = $pdo->prepare('UPDATE `pm_schedule` SET `duedate` = ?, `status` = ? WHERE `id` = ?');
    $sql->execute(array($duedate, $status, $id));
} catch(PDOException $e) {
    echo $e->getMessage();
}

PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION This helps you find the error

With the try and catch you can get an echo an error message of where and why it fails.

回答3:

Here is very good tutorial to understand PDO

And correct way is:

// Named Placeholders
$sSql  = "UPDATE mytable SET FName = :FName, LName = :LName, Age = :Age, Gender = :Gender WHERE ID = :ID;";

// PDO prepared statement
$oSth = $oDbh->prepare($sSql);

// Bind Named Placeholders
$oSth->bindParam(":FName", $FName, PDO::PARAM_STR);
$oSth->bindParam(":LName", $LName, PDO::PARAM_STR);
$oSth->bindParam(":Age", $Age, PDO::PARAM_INT);
$oSth->bindParam(":Gender", $Gender, PDO::PARAM_STR);
$oSth->bindParam(":ID", $ID, PDO::PARAM_INT);

// Execute PDO with condition
if ($oSth->execute()) {
    // Get Affected row
    $iAffectedRows = $oSth->rowCount();
    $oSth->closeCursor();
    return $iAffectedRows;
} else {
    // PDO error, could also be caught in a try/catch statement
    $errorMsg = $oSth->errorInfo();
    error_log(json_encode($errorMsg));
}

来源：https://stackoverflow.com/questions/14747584/correct-way-to-write-pdo-update-statements

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php

mysql

pdo