Question

我是MYSQl的新手，请帮帮我.. 以下查询部分工作正常，但对于某些行，它的值加倍，当两个表在两行或更多行中具有相同的日期时会发生这种情况，例如此处2015-08-11在第一个表中为3，在另一个表中为2。

select all_dates.value1 as "Date",
sum(coalesce(g.Qty1, '-')) as "Inward(B_Qty)",
sum(coalesce(f.Qty2, '-')) as "Outward(B_Qty)"
from
(   select distinct Date1 as value1 from inward  where Name = 'A'  union 
    select distinct Date2 from outward where Name = 'A'
) as all_dates
left join inward g 
on g.Date1 = all_dates.value1  and g.Name = 'A'
left join outward f 
on f.Date2 = all_dates.value1 and f.Name = 'A' group by all_dates.value1,f.Date2

  table no. 1 :- Inward
Name   Qty1       Date1        
 A    25000    2015-08-11                      
 A    15000    2015-08-12 
 A    45000    2015-08-11 
 B   150000    2015-09-11 
 B    85000    2015-07-08 
 B    15000    2015-07-08 


table no 1:Outward
Name   Qty2     Date2
 A     15000    2015-08-01 
 A     25000    2015-08-09 
 A     15000    2015-08-11 
 A     45000    2015-08-11 
 B     25000    2015-07-25

预期的输出

 Date           Inward       Outward
2015-08-11       70000        60000 
2015-08-09           -        25000
2015-08-01           -        15000
2015-08-12       15000            -

实际输出：

Date       Inward(B_Qty)  Outward(B_Qty)   
2015-08-01          0           15000 
2015-08-09          0           25000 
2015-08-11     140000          120000 
2015-08-12      15000               0

实际输出的第三行是值的两倍。为什么它发生了不知道。

Answer 1

尝试这种方式：

select all_dates.value1 as "Date",
sum(coalesce(g.Qty1, '-')) as "Inward(B_Qty)",
sum(coalesce(f.Qty2, '-')) as "Outward(B_Qty)"
from
(   select distinct value1 from (Select Date1 as value1 from inward  where Name = 'A'  union
    select Date2 from outward where Name = 'A') as TmpDates
) as all_dates
left join inward g
on g.Date1 = all_dates.value1  and g.Name = 'A'
left join outward f
on f.Date2 = all_dates.value1 and f.Name = 'A' group by all_dates.value1,f.Date2

Answer 2

尝试加入已经包含每Date1，Date2总和的派生表：

select all_dates.value1 as `Date`,
       coalesce(`Inward(B_Qty)`, '-') as `Inward(B_Qty)`,
       coalesce(`Outward(B_Qty)`, '-') as `Outward(B_Qty)`
from
(   
  select distinct Date1 as value1 from inward  where Name = 'A'  union 
  select distinct Date2 from outward where Name = 'A'
) as all_dates
left join 
(  
  select `Date1`, sum(Qty1) AS `Inward(B_Qty)`
  from inward
  where Name = 'A' 
  group by `Date1`
) as g 
on g.Date1 = all_dates.value1 
left join
(  
  select `Date2`, sum(Qty2) AS `Outward(B_Qty)`
  from outward 
  where Name = 'A' 
  group by `Date2`
) as f 
on f.Date2 = all_dates.value1 
group by all_dates.value1

Demo here

如何更正以下查询

2 个答案: