Mysql查詢 - 分組結果

Question

我有2個表格，基本上我喜歡做的是將結果或計數組合在一起進行顯示。嘗試了不同版本的mysql語句，但沒有得到任何地方。

的2個示例表格是：

tbl_One 
index O_priority 
1   low 
2   medium 
3   high 

tbl_Two 
t_priority 
2 
1 
3 
3 
2 
3 
1 
1 
1 

expected results: 
low = 4 
medium = 2 
high = 3 

Answer 1

SELECT T1.O_priority,T2.c FROM tbl_One as T1 LEFT JOIN (SELECT count(*) as c,t_priority FROM tbl_Two GROUP BY t_priority) as T2 ON T1.index = T2.t_priority; 

Answer 2

加入表，則組的結果：

SELECT tbl_One.O_priority, COUNT(*) 
FROM  tbl_One JOIN tbl_Two ON tbl_Two.t_priority = tbl_One.index 
GROUP BY tbl_One.index 

查看它sqlfiddle。

Answer 3

簡單的東西，你可以，試試這個：

SELECT count(o.index) as `index`, o.O_priority 
FROM tbl_One o join tbl_two t on t.t_priority = o.index 
group by t.t_priority; 

SQL Fiddle