Question

我有以下查询，即选择3个匹配且在第二个表中不存在的条目组。

我需要找到一种方法通过'count_result'返回找到的组数，而不是单个条目ID，如下所示。

我怎样才能做到这一点？

SELECT COUNT(sub.entry_id) as count_result
FROM exp_submissions AS sub
LEFT JOIN exp_judging_portfolios AS jud1 ON sub.entry_id = jud1.entry_id_1
LEFT JOIN exp_judging_portfolios AS jud2 ON sub.entry_id = jud1.entry_id_2
LEFT JOIN exp_judging_portfolios AS jud3 ON sub.entry_id = jud1.entry_id_3
WHERE jud1.entry_id_1 IS NULL
AND jud2.entry_id_2 IS NULL
AND jud3.entry_id_3 IS NULL
AND sub.member_group = 6
AND sub.type_id = 1
GROUP BY sub.member_id, sub.portfolio_number
HAVING count(sub.portfolio_number) = 3

Answer 1

没有必要的子查询。

SELECT COUNT(DISTINCT(sub.member_id, sub.portfolio_number)) as count_result
FROM exp_submissions AS sub
LEFT JOIN exp_judging_portfolios AS jud1 ON sub.entry_id = jud1.entry_id_1
LEFT JOIN exp_judging_portfolios AS jud2 ON sub.entry_id = jud1.entry_id_2
LEFT JOIN exp_judging_portfolios AS jud3 ON sub.entry_id = jud1.entry_id_3
WHERE jud1.entry_id_1 IS NULL
AND jud2.entry_id_2 IS NULL
AND jud3.entry_id_3 IS NULL
AND sub.member_group = 6
AND sub.type_id = 1
GROUP BY sub.member_id, sub.portfolio_number
HAVING count(sub.portfolio_number) = 3

Answer 2

使用您的查询作为另一个只计算结果的查询的来源：

SELECT COUNT(*) FROM (
      -- YOUR QUERY GOES HERE --
) AS t

计数3组？可能？

2 个答案: