Question

我想要匹配两张桌子。当记录在同一组名中时，我希望sourcelist中的referbyname与namejoin匹配

我想以一对一的方式加入这两张桌子。 targetjoin中的联系人具有多个具有相同名称的记录类型。我想根据记录类型名称

的层次结构设置进行某种类型的不同连接

例如：如果记录与两个相同名称的记录类型匹配，则RecordType：TypeA将仅匹配，依此类推。

sourcelist：

           ID  GroupName  Name          ReferredbyName        
           1   A          John Smith    Sally Bosh
           2   A          Craig Miller  Sally Smith
           3   A          Fulton Fork   Spoon Knife
           4   B          Joe Sample    George Test

targetjoin：

   ID   GroupName     Name         RecordType
   101   A            Sally Bosh   TypeA
   102   A            Sally Bosh   TypeB
   103   A            Sally Smith  TypeC
   104   A            Sally Smith  TypeD
   105   B            George Test  TypeF

我的结果：

    | id | groupname |         name | referredbyname |  id | groupname |        name | recordtype |
    |----|-----------|--------------|----------------|-----|-----------|-------------|------------|
    |  2 |         A | Craig Miller |    Sally Smith | 103 |         A | Sally Smith |      TypeC |
    |  1 |         A |   John Smith |     Sally Bosh | 102 |         A |  Sally Bosh |      TypeB |
    |  1 |         A |   John Smith |     Sally Bosh | 101 |         A |  Sally Bosh |      TypeA |
    |  2 |         A | Craig Miller |    Sally Smith | 104 |         A | Sally Smith |      TypeD |
    |  4 |         B |   Joe Sample |    George Test | 105 |         B | George Test |      TypeF |

此结果为我提供了所有可能匹配的一对多连接重复ID

我希望得到这样的结果：

    | id | groupname |         name | referredbyname |  id | groupname |        name | recordtype |
    |----|-----------|--------------|----------------|-----|-----------|-------------|------------|
    |  2 |         A | Craig Miller |    Sally Smith | 103 |         A | Sally Smith |      TypeC |
    |  1 |         A |   John Smith |     Sally Bosh | 101 |         A |  Sally Bosh |      TypeA |
    |  4 |         B |   Joe Sample |    George Test | 105 |         B | George Test |      TypeF |

这是我到目前为止所得到的

select a.*, b.*
from sourcelist a 
join targetjoin b
on a.groupname=b.groupname
and 
case
when b.recordtype in ('TypeA') and a.referredbyname=b.name then 1
when b.recordtype in ('TypeB') and a.referredbyname=b.name then 2
when b.recordtype in ('TypeC') and a.referredbyname=b.name then 3
when b.recordtype in ('TypeD') and a.referredbyname=b.name then 4
when b.recordtype in ('TypeE') and a.referredbyname=b.name then 5
when b.recordtype in ('TypeF') and a.referredbyname=b.name then 6
else 0
end in (1,2,3,4,5,6)
order by a.groupname

架构：http://sqlfiddle.com/#!9/eb97f

感谢您的帮助！

Answer 1

SELECT x.* 
  FROM targetjoin x
  JOIN
     ( SELECT name
            , MIN(recordtype) recordtype 
         FROM targetjoin 
        GROUP 
           BY name
     ) y
    ON y.name = x.name
   AND y.recordtype = x.recordtype;

这个问题的最后一部分留给读者练习。

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