SELECT ss.quan FROM `stock` as ss
          JOIN `order_record` as r ON r.order_id = ss.order_id
          WHERE ss.from = "c"
          AND r.from = "c"
          AND r.status = "ing"
          AND ss.prod_id = 120
          GROUP BY ss.order_id

this is exported by a number of databases:

32

GROUP BY ss.order_id 32
order_id

this may be well understood by
. I just want to ask that the initial numerals are correct
when sum is not correct
what should I pay attention to when using sum? Can"t be so direct sum?