Update multiple rows with one query

Question

How can I update hundreds of rows at once?

Like: UPDATE table SET a = ? WHERE b = ? AND c = 1

but for many rows. The ? parameters a

Answer 1

To do it in a single run of a query, you'd need to use a CASE and assemble the parameters programmatically. SQL doesn't support variadic prepared statements, and only simple values can be parameterized.

Alternatively, define a statement to only take data for one row at a time and run the query in a loop. Repeated execution is how prepared statements are designed to be used for cases like this.

try {
    $query = $db->prepare('UPDATE table SET a = ? WHERE b = ? AND c = 1');
    foreach ($as as $i => $a) {
        $query->execute(array($a, $bs[$i]));
    }
} catch (PDOException $e) {
    ...
}

Answer 2

Another way would be to insert your key value pairs (all at once) into a temporary table then do something like this:

UPDATE table t
SET t.a = (SELECT p.a FROM tmp p WHERE p.b = t.b)
WHERE t.b IN (SELECT p.b FROM tmp p) AND t.c = 1

Answer 3

Use the CASE method as described in the link you provided, but build the query dynamically with the values you want.

Likely, this will be built with a for loop similar to how you're already doing it, but you will end up with a single query rather than querying your database every iteration.