Question

要求：我想显示特定B_Name的股票，如果日期相同则会显示在同一行上，如果日期不相同则会显示在不同的行上，并且“ - ”将指定

两张表格gr和frosted

table gr:
B_Name  B_Date         B_Qty   
A       2015-08-11     15000    
A       2015-08-15     25000      
A       2015-08-31     20000

表格结霜：

M_Name       M_Date       M_Qty   
    A       2015-08-11    15000    
    A       2015-08-25    25000      
    B       2015-08-20    20000 
    A       2015-08-15    15000

关注输出：

             for Particular B_Name like here (A)
     Date        Inward(B_Qty) Outward(M_Qty)
    2015-08-11     15000      15000
    2015-08-15     25000      15000
    2015-08-31     20000        -
    2015-08-25      -         25000

我尝试了加入和联盟，但它没有按照我的要求工作。

Answer 1

您希望表gr中的记录在表格中没有匹配，反之亦然。所以你需要一个完整的外连接，MySQL不支持。

一种可能的解决方法：首先使用联合查询获取所有日期，然后再次将表连接外部。

select 
  alldates.value as "Date",
  coalesce(g.b_qty, '-') as "Inward(B_Qty)",
  coalesce(f.m_qty, '-') as "Outward(B_Qty)"
from
(
  select b_date as value from gr
  where b_name = 'A'
  union 
  select m_date from frosted
  where m_name = 'A'
) all_dates
left join gr g on g.b_date = all_dates.value
               and g.b_name = 'A'
left join frosted f on f.m_date = all_dates.value
                    and f.m_name = 'A'

Answer 2

我试过并找到了所需的结果：

SELECT table1.bdate as "Date",coalesce(t1.B_Qty,'-') as "Inward(B_Qty)",coalesce(t2.M_Qty,'-') as "Outward(M_Qty)" FROM ( select B_date as bdate,B_Name as bname from gr union select M_Date as mdate,M_Name as mname from frosted) as table1 LEFT JOIN gr as t1 ON t1.B_Date = table1.bdate LEFT JOIN frosted as t2 ON t2.M_Date = table1.bdate WHERE table1.bname like 'A'

如何在MySQL中编写以下输出的查询

2 个答案: