Sql 通过特定列从表中查找不同值的方法

下面是一个由如下数据组成的表格：

StandardName|Username    |RType
------------|------------|--------
Department  |Department  |  Position
Division    |Division    |  Entity
Division    |Division    |  Position
Plant       |Plant       |  Entity
Section     |Section     |  Position
SubDivision |Sub-Division|  Entity
SubDivision |Subdivision |  Position
SubSection  |Subsection  |  Position
Unit        |Unit        |  Entity

我希望所有的StandardName和UserName后跟Rtype='Entity'，如果Rtype='Position'，它将只获得与Rtype'Entity'不关联的StandardName

为此，我做了这样的查询

SELECT DISTINCT u.StandardName, u.UserName ,ISNULL(e.RType,'position') AS RType
from (
     SELECT  DISTINCT StandardName,UserName
     from Table1 AS ee where   RType = 'Entity'  
     UNION
     SELECT  DISTINCT StandardName, UserName
     from Table1 AS pp where  RType = 'position' 
) u
LEFT OUTER JOIN (
     select UserName,StandardName,RType 
     from Table1 WHERE RType='Entity' 
) e on e.StandardName = u.StandardName
 ORDER BY Rtype

然后输出为

StandardName|Username    |RType
------------|------------|--------
Division    |Division    |  Entity
Plant       |Plant       |  Entity      
SubDivision |Sub-Division|  Entity
SubDivision |Subdivision |  Entity       
Unit        |Unit        |  Entity
Department  |Department  |  Position
Section     |Section     |  Position
SubSection  |Subsection  |  Position

在这里，如果是“细分”，它会显示两次，而需要使用“实体”RType显示一次

预期输出应为--

---

SQLFIDLE这是根据您的需求翻译的sql语句：

 -- gimme all things that are entity
 select StandardName, UserName, RType 
   from Table1
   where RType = 'Entity'  
 union   
 -- and all things that have no entity-entry
   select StandardName, UserName, RType from Table1 as k
   where rtype = 'Position' and not exists (
       select 1 
       from table1 as t 
       where t.standardname = k.standardname 
         and t.rtype = 'Entity'  
   )

没有您的“distincs”，但您得到以下结果：

StandardName    UserName        RType
----------------------------------------
Division        Division        Entity
Plant           Plant           Entity
SubDivision     Sub-Division    Entity
Unit            Unit            Entity
Department      Department      Position
Section         Section         Position
SubSection      Subsection      Position

---

您没有任何重复的

“实体”

-条目-因此不需要任何不同的条目

这是根据您的需求翻译的sql语句：

 -- gimme all things that are entity
 select StandardName, UserName, RType 
   from Table1
   where RType = 'Entity'  
 union   
 -- and all things that have no entity-entry
   select StandardName, UserName, RType from Table1 as k
   where rtype = 'Position' and not exists (
       select 1 
       from table1 as t 
       where t.standardname = k.standardname 
         and t.rtype = 'Entity'  
   )

没有您的“distincs”，但您得到以下结果：

StandardName    UserName        RType
----------------------------------------
Division        Division        Entity
Plant           Plant           Entity
SubDivision     Sub-Division    Entity
Unit            Unit            Entity
Department      Department      Position
Section         Section         Position
SubSection      Subsection      Position

---

您没有任何重复的

“实体”

-条目-因此不需要任何不同的条目

对于每个StandardName，您希望使用“实体”行，但如果不存在，则使用“位置”行。这是一个简单的行号任务：

with cte as 
 ( 
   select
      StandardName
     ,Username
     ,RType
     ,row_number() 
      over (partition by StandardName  -- for each StandardName
            order by RType) as rn      -- sort to get Entity first
   from Table1
 )
select
   StandardName
  ,Username
  ,RType
from cte
where rn = 1
order by
   RType
  ,Username
;

---

请参见

，了解您希望使用“实体”行的每个标准名称，但如果不存在，则使用“位置”行。这是一个简单的行号任务：

with cte as 
 ( 
   select
      StandardName
     ,Username
     ,RType
     ,row_number() 
      over (partition by StandardName  -- for each StandardName
            order by RType) as rn      -- sort to get Entity first
   from Table1
 )
select
   StandardName
  ,Username
  ,RType
from cte
where rn = 1
order by
   RType
  ,Username
;

请参见试一试：

select * from Employees 
where rtype = 'Entity' 
or
standardname in (
select standardname from Employees 
where rtype = 'Position' and 
standardname not in 
(select standardname from employees where rtype = 'Entity'))
order by rtype,standardname

试试这个：

select * from Employees 
where rtype = 'Entity' 
or
standardname in (
select standardname from Employees 
where rtype = 'Position' and 
standardname not in 
(select standardname from employees where rtype = 'Entity'))
order by rtype,standardname

---

这是一个优先级查询。帕特里克的方法是一种很好的方法，特别是当只有两种类型时

另一种方法使用

行编号（）

：

---

这是一个优先级查询。帕特里克的方法是一种很好的方法，特别是当只有两种类型时

另一种方法使用

行编号（）

：

---

用户名

Sub-Division

和

Subdivision

应该相等，不是吗？用户名

Sub-Division

和

Subdivision

应该相等，不是吗。。？