[英]Join two queries with COUNT from the same table in MySQL
我在同一個表中運行了兩個查詢:
SELECT id, COUNT(up)
FROM comentarios
WHERE up = 1
GROUP BY id
和
SELECT id, COUNT(down)
FROM comentarios
WHERE down = 2
GROUP BY id
我嘗試過這樣的事情但不起作用
SELECT t1.id, COUNT(t1.up), t2.id, COUNT(t2.down)
FROM (SELECT id, up FROM comentarios WHERE up = 1 GROUP BY id) t1
JOIN (SELECT id, down FROM comentarios WHERE down = 2 GROUP BY id) t2
ON t1.id = t2.id
也許需要一個完整的外部連接?
在 MySQL 中執行此操作的最佳方法是什么?
select id,
sum(case when up = 1 then 1 end) as UpCount,
sum(case when down = 2 then 1 end) as DownCount
from comentarios
group by id
SELECT id,
SUM(CASE WHEN up = 1 THEN 1 ELSE 0 END) AS UpCount,
SUM(CASE WHEN down = 2 THEN 1 ELSE 0 END) AS DownCount
FROM comentarios
GROUP BY id
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