mysql - 如何让这个查询正确？

Question

这是我的第一张 table

Type      LimitDays
-----------------
leave        15
absent       15
vacation     15

这是我的第二张 table

Name      type      UseDays
---------------------------
Chuck     leave         3

现在我想要的是连接两个表..并像这样显示..

Type       LimitDays    UseDays
--------------------------------
leave         15          3
absent        15          0
vacation      15          0

这是我已经完成的..但是

SELECT   
    Leave,
    Counter,
    (SELECT SUM(LeaveTbl.NumDays) AS Expr1
     FROM  LeavetypTbl 
     INNER JOIN LeaveTbl ON  LeavetypTbl.Leave = LeaveTbl.Leave
     GROUP BY LeavetypTbl.Leave, LeavetypTbl.Counter) AS Expr1
FROM     
    LeavetypTbl AS LeavetypTbl_1

结果是错误的..大声笑还是不对..结果是这样的

Type       LimitDays    UseDays
--------------------------------
leave         15          3
absent        15          3
vacation      15          3

Answer 1

如果您使用的是 MySQL:

SELECT LeavetypTbl.Leave, LeavetypTbl.Counter, IFNULL(SUM(LeaveTbl.NumDays), 0)
FROM LeavetypTbl LEFT JOIN LeaveTbl ON LeavetypTbl.Leave = LeaveTbl.Leave
GROUP BY LeavetypTbl.Leave