Question

I have an array with 3,000+ rows fomrated like this

$COUNTS = array(
1=>5,
2=>22,
3=>120,
4=>0,
....
);

where the key represents an ID and value is the calculated COUNT…

I need to update all the rows in my table with these new values (with php)…

so right now I am updating them one by one
(simplified) like

foreach($COUNTS as $id=>$count){
mysql_query("UPDATE categories SET count=$count WHERE id=$id");
}

I would need to make 3,000+ queries, to make a simple update….

can this be done in one query or any other less resource consuming way? maybe generating a csv file and updating on the fly or something?

Answer 1

You can try something like

UPDATE categories c
INNER JOIN 
(
   SELECT 1 as id, 23 as `cnt`
   UNION
   SELECT 2 as id, 25 as `cnt`
   -- UNION  etc
)a
ON  c.id = a.id
SET c.`count` = a.cnt