Question

$SQL = "SELECT pc.dist_id, pc.route, pc.types,
        COUNT( pc.types = '$type' ) total,
        COUNT( pc.types = '$type' AND pc.options = '1') callbacks

        FROM per_call pc
        WHERE pc.types = '$type'
        GROUP BY pc.dist_id, pc.route, pc.types
        ORDER BY pc.dist_id, pc.route";

In short, I guess I’m asking how COUNT works with multiple columns inside the ().

Answer 1

Count will work as well :

SELECT pc.dist_id, pc.route, pc.types,
COUNT( CASE WHEN pc.types = '$type' THEN 1 END) total,
COUNT( CASE WHEN pc.types = '$type' AND pc.options = '1' THEN 1 END) callbacks

FROM per_call pc
WHERE pc.types = '$type'
GROUP BY pc.dist_id, pc.route, pc.types
ORDER BY pc.dist_id, pc.route

Note: it works because COUNT returns count of the number of non-NULL values, and CASE has default ELSE NULL …