MySQL的左由

Question

嗨，我加入，和组使用此MySQL的代码生成下面这样的数据：

代码：

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 

当我将WHERE条件那只能说明具有值的LeaveType。我如何显示包括null在内的所有leavetype（像在第一张图片中）？

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

移动idstafftable条件的加入，而不是其中：

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