Mysql SQL联接父记录和子记录并获取父记录和子记录的计数

我有这个问题，这让我很难找出问题所在，谢谢你的建议

 SELECT
  cooperatives.island, cooperatives.id,
  COUNT(
    CASE WHEN members.gender = 'Male' THEN 1 ELSE NULL END
  ) AS males,
  COUNT(
    CASE WHEN members.gender = 'Female' THEN 1 ELSE NULL END
  ) AS females,
  COUNT(members.gender) AS genderall
FROM
  cooperatives
JOIN members ON cooperatives.id= members.c_id
WHERE
  1 = 1 
GROUP BY
  cooperatives.island

我想做的就是得到这样的结果

这是可行的，但我需要添加的是另一个专栏，其中将显示每个岛屿的一些合作社。

我想您想要：

SELECT c.island, COUNT(DISTINCT c.id) as num_cooperatives,
       SUM(m.gender = 'Male') AS males,
       SUM(m.gender = 'Female') AS females,
       COUNT(m.gender) AS genderall
FROM cooperatives c JOIN
     members m
     ON c.id = m.c_id
GROUP BY c.island;

我怀疑你想要：

SELECT c.island, COUNT(DISTINCT c.id) as num_cooperatives,
       SUM(m.gender = 'Male') AS males,
       SUM(m.gender = 'Female') AS females,
       COUNT(m.gender) AS genderall
FROM cooperatives c JOIN
     members m
     ON c.id = m.c_id
GROUP BY c.island;

---

当您在计数时使用case，则不要使用else语句。当您在计数时使用case，则不要使用else语句。