php - mysql - querying 2 tables in one query and creating the difference of the two results. -
i'm running 2 queries in php, take result of each create difference:
$sec = 3600; $sql = "select sum(revenue) c revenue_log entry_date between (date_sub(now(), interval $secs second)) , (now())"; $res = $this->db->query($sql)->result_array(); $rev = $res[0]['c']; $sql = "select sum(cost) c cost_log entry_date between (date_sub(now(), interval $secs second)) , (now())"; $res = $this->db->query($sql)->result_array(); $cost = $res[0]['c']; $profit = $rev - $cost;
is possible combine 1 query easily? how?
you need run each query individually join them derived tables:
select r,c, r-c difference ( select sum(revenue) r revenue_log entry_date between (date_sub(now(), interval $secs second)) , (now()) ) revenue join ( select sum(cost) c cost_log entry_date between (date_sub(now(), interval $secs second)) , (now()) ) cost;
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