Mysql group_concat of repeated keys and count of repetition of multiple columns in 1 query ( Query Optimization )

Question

This question is regarding query optimization to avoid multiple call to database via PHP.

So Here is scenario, I have two tables one contains information you can cal

Answer 1

Judging from your quote it seems to me you want to do something like this (SQLfiddle):

SELECT
  m.info1,
  m.info2,
  COUNT(DISTINCT CONCAT(m.key1, ' ', m.key2)) key_count,
  GROUP_CONCAT(DISTINCT CONCAT(m.key1, ' ', m.key2) ORDER BY m.key1, m.key2) key_pairs,
  COUNT(DISTINCT p.serial) serial_count,
  GROUP_CONCAT(DISTINCT p.serial ORDER BY p.serial) serials,
  COUNT(DISTINCT p.product_data) data_count,
  GROUP_CONCAT(DISTINCT p.product_data ORDER BY p.product_data) product_data
FROM
  main_info m INNER JOIN
  product1 p ON p.key1 = m.key1 AND p.key2 = m.key2
WHERE
  p.serial < 10
GROUP BY
  m.info1,
  m.info2

Count distinct values and list them, is this correct? You can't just group by info1, info2 and also have columns for key1 or key2 in the result (e.g. min(key1) or max(key2) would work). I adjusted this in the query above, although it is quite different from your result it might be what you actually need, maybe with a few changes.