MySQL的左由

Question

嗨，我加入，和組使用此MySQL的代碼生成下面這樣的數據：

代碼：

SELECT L.LEAVETYPE, LA.IDLEAVETYPE, LA.IDLEAVETABLE, SUM(LA.NOOFDAYS) 
FROM LEAVETYPE AS L 
LEFT JOIN LEAVEAPPLICATION AS LA ON LA.IDLEAVETYPE = L.IDLEAVETYPETABLE 
GROUP BY L.LEAVETYPE 

當我將WHERE條件那隻能說明具有值的LeaveType。我如何顯示包括null在內的所有leavetype（像在第一張圖片中）？

SELECT L.LEAVETYPE, LA.IDLEAVETYPE, LA.IDLEAVETABLE, SUM(LA.NOOFDAYS) 
FROM LEAVETYPE AS L 
LEFT JOIN LEAVEAPPLICATION AS LA ON LA.IDLEAVETYPE = L.IDLEAVETYPETABLE 
WHERE LA.IDSTAFFTABLE='24' 
GROUP BY L.LEAVETYPE 

Answer 1

移動idstafftable條件的加入，而不是其中：

LEFT JOIN LEAVEAPPLICATION AS LA ON LA.IDLEAVETYPE = L.IDLEAVETYPETABLE AND LA.IDSTAFFTABLE='24'