T：SQL：从行中选择值作为列

Question

我有一个用于“个人档案”的表，以行样式存储个人档案属性值，例如：

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

和另一个用于属性定义的表：

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

如何使用PIVOT或以任何其他方式以这种方式显示它：

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

Answer 1

不用PIVOT关键字就可以轻松完成此操作，只需将其分组即可

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

您也可以使用PIVOT关键字执行此操作

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