使用一个查询更新多行

Question

How can I update hundreds of rows at once?

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

but for many rows. The ? parameters are arrays...

I read this answer but it uses CASE and I don't think I can do that...

---

Right now I have something like this:

foreach($values as $key => $value)
  $res = $pdo->prepare('UPDATE table SET a = ? WHERE b = ? AND c = 1');
  $res->execute(array($value, $key));
}

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

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.

Answer 3

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