分組大量在一起並形成一個上即時AMT列

Question

我有一個MySQL數據庫是這樣的：

id - join_id - bool 
1 - 32 - 1 
2 - 32 - 0 
3 - 32 - 1 
4 - 32 - 1 

我想查詢此：

join_id - bool (- amount) 
32 - 1 - 3 (aka there are 3 instances where the join_id and bool are 32 and 1); 
32 - 0 - 1 (aka there is 1 instances where the join_id and bool are 32 and 0); 

任何關鍵詞，或名字真的很有幫助。

Answer 1

這是你在找什麼，我認爲：

SELECT join_id, bool, COUNT(id) AS amount FROM mytable GROUP BY join_id,bool