我有一份工作的SQL声明用于计算工资和计算工作日的数量，SO的一位成员在这里帮助我解决了这个问题。然而，问题是结果只出现在那个时期有效的劳动力。我真正想要的是结果必须显示所有劳动力（在tbl_labor），无论他是否在那个时期工作过。
select
lab.lb_name,
max(days),
sum(prod.pdtn_qty * pdWk.pd_cost / 12) as Total
from
tbl_labor as lab,
tbl_production as prod,
tbl_pdWk_process as pdwk,
(select pdn2.lb_id, count(pdn2.lb_id) as days from
(select lb_id
from tbl_production pdn1
where pdn1.pdtn_date >= #9/5/2012#
and pdn1.pdtn_date <= #2012-09-20#
group by lb_id, pdtn_date ) as pdn2
group by pdn2.lb_id) as pdn3
where prod.pdtn_date >= #9/5/2012#
and prod.pdtn_date <= #2012-09-20#
and prod.lb_id = lab.lb_id
and prod.pd_making_id = pdwk.pd_making_id
and lab.lb_id = pdn3.lb_id
group by lab.lb_name
以下是我的相关表格：
tbl_labor
lb_id | lb_name | lb_OT ($/day) | If_social_sec
1 | John | 10 | yes
2 | Mary | 10 | no
3 | Jane | 10 | no
tbl_production
pdtn_date | lb_id | pdtn_qty(pcs) | pd_making_id
5/9/12 | 1 | 200 | 12
5/9/12 | 1 | 40 | 13
5/9/12 | 2 | 300 | 12
7/9/12 | 1 | 48 | 13
13/9/12 | 2 | 220 | 14
15/9/12 | 1 | 20 | 12
20/9/12 | 1 | 33 | 14
21/9/12 | 2 | 55 | 14
21/9/12 | 1 | 20 | 12
tbl_pdWk_process
pd_making_id | pd_cost($/dozen) | pd_id
12 | 2 | 001
13 | 5 | 001
14 | 6 | 002
答案 0 :(得分：4)
替换旧式连接
from
tbl_labor as lab,
tbl_production as prod,
...
where
lab.fld1 = prod.fld1
更新的LEFT JOIN
from
tbl_labor as lab
LEFT JOIN tbl_production as prod ON lab.fld1 = prod.fld1
...
编辑：
在原始代码中
from
tbl_labor as lab,
tbl_production as prod
...
where ...
prod.lb_id = lab.lb_id
...
在tbl_production和tbl_labor表之间创建内部联接。 它需要用更新的LEFT JOIN
替换from
tbl_labor as lab
LEFT JOIN tbl_production as prod ON lab.lb_id = prod.lb_id
...