T：SQL：從行作爲列選擇值

Question

我的配置文件的表存儲行樣式配置文件屬性值，例如：

[ProfileID]  [PropertyDefinitionID]  [PropertyValue] 
1    6       Jone 
1    7       Smith 
1    8       Mr 
1    3       50000 

，另一個表屬性定義：

[PropertyDefinitionID] [PropertyName] 
6      FirstName 
7      LastName 
8      Prefix 
3      Salary 

如何使用PIVOT或任何其他方式來顯示它在這樣：

[ProfileID] [FirstName] [LastName] [Salary] 
1   Jone  Smith  5000 

Answer 1

這很容易做到這一點沒有PIVOT關鍵字，只是分組

select 
    P.ProfileID, 
    min(case when PD.PropertyName = 'FirstName' then P.PropertyValue else null end) as FirstName, 
    min(case when PD.PropertyName = 'LastName' then P.PropertyValue else null end) as LastName, 
    min(case when PD.PropertyName = 'Salary' then P.PropertyValue else null end) as Salary 
from Profiles as P 
    left outer join PropertyDefinitions as PD on PD.PropertyDefinitionID = P.PropertyDefinitionID 
group by P.ProfileID 

你也可以用PIVOT關鍵字

select 
    * 
from 
(
    select P.ProfileID, P.PropertyValue, PD.PropertyName 
    from Profiles as P 
     left outer join PropertyDefinitions as PD on PD.PropertyDefinitionID = P.PropertyDefinitionID 
) as P 
    pivot 
    (
     min(P.PropertyValue) 
     for P.PropertyName in ([FirstName], [LastName], [Salary]) 
    ) as PIV 

UPDATE做到這一點：對於性能的動態數 - 看看Increment value in SQL SELECT statement

Answer 2

它看起來像你可能有一個未知數PropertyName's，你需要把它變成列。如果是這樣的話，那麼你可以使用動態sql來產生結果：

DECLARE @cols AS NVARCHAR(MAX), 
    @query AS NVARCHAR(MAX) 

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(PropertyName) 
        from propertydefinitions 
      FOR XML PATH(''), TYPE 
      ).value('.', 'NVARCHAR(MAX)') 
     ,1,1,'') 

set @query = 'SELECT profileid, ' + @cols + ' from 
      (
       select p.profileid, 
        p.propertyvalue, 
        d.propertyname 
       from profiles p 
       left join propertydefinitions d 
        on p.PropertyDefinitionID = d.PropertyDefinitionID 
      ) x 
      pivot 
      (
       max(propertyvalue) 
       for propertyname in (' + @cols + ') 
      ) p ' 

execute(@query) 

請參閱SQL Fiddle with Demo。