Question

Say I’ve 5 rows with id, catname and order fields:

+----+----------+-----+  
| id | catname  |order|
+----+----------+-----+  
|  1 | cat1     |   2 |
|  2 | cat2     |   1 |
|  3 | cat3     |   3 | 
|  4 | cat4     |   5 |
|  5 | cat5     |   4 |
+----+----------+-----+  

and I want to update the order of these 5 categories from an array, e.g.:

array(1 => 3, 2 => 4, 3 => 5, 4 => 1, 5 => 2)

What is the best practice? To select each row and update order fields with its corresponding order in array? Or to create a new table containing order array of all these categories and use it for ordering and linking the two tables with a join statement using for example userid?

Answer 1

If you want to do it in one query, you can generate your SQL query as follows (assuming the keys are the existing order values):

$orders = array(
    1 => 3,
    2 => 4,
    3 => 5,
    4 => 1,
    5 => 2,
);

$sql = 'UPDATE category SET order = CASE order ';

foreach ($orders as $old => $new) {
    $sql .= "WHEN $old THEN $new ";
}

$sql .= 'END';

If the keys are the id entries, use CASE id instead of CASE order.