我有一个具有以下字段的大文件:
表1:
+---------+--------+-----------+
| User_Id | Key_Id | Value |
+---------+--------+-----------+
| 100 | 74 | 37 |
| 100 | 65 | Male |
| 100 | 279 | G235467 |
+---------+--------+-----------+
我还有另一个文件,该文件告诉每个" key_id"(它们是列名(,例如
表2:
+--------+------------------+
| Key_Id | Key |
+--------+------------------+
| 65 | Gender |
| 66 | Height |
| 74 | Age |
| 279 | ReferenceNo |
我想使用表2的密钥列中的key_id名称创建一个表,将所有值从表1转移到表2中,但还包括从表1中包含user_id,因为这与个人有关。<<<<<<<<<<<<<<<<<</p>
ps。表2具有将近300个键,需要变成单个字段
所以最终我想要一张看起来像这样的桌子:
+---------+---------+--------+-------+--------------+--------+
| User_Id | Gender | Height | Age | ReferenceNo | etc |
+---------+---------+--------+-------+--------------+--------+
| 100 | Male | | 37 | G235467 | |
使每个user_id都是一行,所有键都是具有其各自值的列
您可以使用下面的动态SQL查询。
查询
declare @sql as varchar(max);
select @sql = 'select t1.[User_Id], ' + stuff((select +
', max(case t2.[Key_Id] when ' + cast([Key_Id] as varchar(100)) +
' then t1.[Value] end) as [' + [Key] + '] '
from Table2
for xml path('')
), 1, 2, '') +
'from Table1 t1 left join Table2 t2 on t1.[Key_Id] = t2.[Key_Id] group by t1.[User_Id];'
exec(@sql);
在此处找到一个演示
您需要在t-sql中使用的300个关键名称的昏迷列表,如此处所述
https://learn.microsoft.com/en-us/sql/t-sql/queries/from-using-pivot-and-unpivot
您可以使用以下枢轴:
Select * from (
Select u.UserId, k.[key], u.[Value] from table1 u
join table2 k on u.keyid = k.keyid ) a
pivot ( max([Value]) for [key] in ([Gender], [Height], [Age], [ReferenceNo]) ) p
对于键的动态列表,您可以使用Dynamic SQL如下:
Declare @cols1 varchar(max)
Declare @query nvarchar(max)
Select @cols1 = stuff((select ','+QuoteName([Key]) from table2 group by [Key] for xml path('')),1,1,'')
Set @Query = 'Select * from (
Select u.UserId, k.[key], u.[Value] from table1 u
join table2 k on u.keyid = k.keyid ) a
pivot ( max([Value]) for [key] in (' + @cols1 + ') ) p '
Select @Query --Check the generated query and execute by uncommenting below query
--exec sp_executesql @Query