Question

I have a table A, with just two columns: ‘id’ and ‘probably’. I need to go over a long list of ids, and determine for each one whether he is in A and has probability of ‘1’. What is the best way to do it?

I figured that it would be best to have 1 big query from A in the beginning of the script, and after that when I loop each id, I check the first query. but than i realized I don’t know how to do that (efficiently). I mean, is there anyway to load all results from the first query to one array and than do in_array() check? I should mention that the first query should had few results, under 10 (while table A can be very large).

The other solution is doing a separate query in A for each id while I loop them. But this seems not very efficient…

Any ideas?

Answer 1

If you have the initial list of ids in array, you can use the php implode function like this:

$query = "select id 
          from A
          where id in (".implode (',', $listOfIds).")
          and probability = 1";

Now you pass the string as first parameter of mysql_query and receive the list of ids with probability = 1 that are within your initial list.