PDO - Update And Set Query (2 arrays) - mysql

Question

So I have two arrays that I need to update and set with in MySQL. item_id [1,2,3] and item_order[2,1,3]
Here is the items table before the array insert:
item_id item_order
1 1 //should become 2
2 2 // should become 1
3 3 // should become 3
The arrays should be in pairs for the insert, 1-2, 2-1, 3-3.
How can I do this with a prepared statement efficiently and how can I test if the array items are indeed numbers?

Answer 1

Assuming you have input like this:
$item_id = array(1, 2, 3);
$item_order = array(2, 1, 3);
// and a PDO connection named $pdo
You can try something like this. (I'm also assuming you have PDO configured to throw exceptions when problems arise).
function all_numbers($input) {
foreach($input as $o) {
if(!is_numeric($o)) {
return false;
}
}
return true;
}
if(count($item_id) != count($item_order)) {
throw new Exception("Input size mismatch!");
}
if(!all_numbers($item_id) || !all_numbers($item_order)) {
throw new Exception("Invalid input format!");
}
$pairs = array_combine($item_id, $item_order);
// now $pairs will be an array(1 => 2, 2 => 1, 3 => 3);
if($pdo->beginTransaction()) {
try {
$stmt = $pdo->prepare('UPDATE `items` SET `item_order` = :order WHERE `item_id` = :id');
foreach($pairs as $id => $order) {
$stmt->execute(array(
':id' => $id,
':order' => $order,
));
}
$pdo->commit();
} catch (Exception $E) {
$tx->rollback();
throw $E;
}
} else {
throw new Exception("PDO transaction failed: " . print_r($pdo->errorInfo(), true));
}
But it might be better to redesign your input - only pass the item_ids in the desired order and compute their item_order values automatically.

Answer 2

Here is an example:
UPDATE mytable
SET myfield = CASE other_field
WHEN 1 THEN 'value'
WHEN 2 THEN 'value'
WHEN 3 THEN 'value'
END
WHERE id IN (1,2,3)