我需要显示数据库中每个人的运行总计,但我只能得到所有人的运行总计,所以这些是我在图片上的表
我已经有了这个问题:
SELECT
id,
studno,
if(type=0,amount,0)debit,
if(type=1,amount,0)credit,
if(type=0,@bal:=@bal+amount,@bal:=@bal-amount) runningTotal
FROM
(SELECT id, studno, amount, 0 type from tblPayables
UNION ALL
SELECT id, studno, amount, 1 type from tblPayments)s, (SELECT @bal:=0)b
ORDER BY studno, id, type;
但问题是我只能得出这个结果:
突出显示的数字应为50,因为它是针对不同的studno
答案 0 :(得分:2)
您必须以每次ID更改时初始化变量的方式编写查询。
假设您可以使用以下列编写查询或视图:
id | studno | debit | credit
---+--------+-------+-------
所以,让我们写下查询:
select id, debit, credit
, @bal := ( -- If the value of the column `studno` is the same as the
-- previous row, @bal is increased / decreased;
-- otherwise, @bal is reinitialized
case
when @studno = studno then @bal + debit - credit
else debit - credit
end
) as balance
@studno := a.studno as studno -- It's important to update @studno
-- AFTER you update @bal
from
(
select @bal := 0
, @studno := 0 -- This variable will hold the previous
-- value of the `studno` column
) as init, -- You must initialize the variables
( -- The above mentioned query or view
select ...
from ...
) as a
order by a.studno, a.id -- It's REALLY important to sort the rows
答案 1 :(得分:0)
正如我在评论中写的那样 - 现有查询交错错误,如果相应应付帐户的付款ID较小,则会失败
这里是查询,它正确交错并计算运行总额,如@Barranka建议的那样:
select studno, amount, @bal := (
case
when @studno = studno then @bal + amount
else amount
end
) as balance,
@studno := studno
from
(
select @bal := 0
, @studno := 0
) as init,
(
select 0 as t, studno, amount, (select count(*) from tblPayables as b where a.id>b.id and a.studno=b.studno) as trN
from tblPayables as a
union all
select 1 as t, studno, -amount, (select count(*) from tblPayments as b where a.id>b.id and a.studno=b.studno) as trN
from tblPayments as a
) as q
order by studno, trN, t