我需要在表中的XML列上执行一个数据透视表,其中XML包含多个具有许多属性的元素.每个元素中的属性始终相同,但元素的数量会有所不同.让我举个例子…
FormEntryId | FormXML | DateCreated
====================================================================================
1 |<Root> | 10/15/2009
| <Form> |
| <FormData FieldName="Username" FieldValue="stevem" /> |
| <FormData FieldName="FirstName" FieldValue="Steve" /> |
| <FormData FieldName="LastName" FieldValue="Mesa" /> |
| </Form> |
|</Root> |
| |
------------------------------------------------------------------------------------
2 |<Root> | 10/16/2009
| <Form> |
| <FormData FieldName="Username" FieldValue="bobs" /> |
| <FormData FieldName="FirstName" FieldValue="Bob" /> |
| <FormData FieldName="LastName" FieldValue="Suggs" /> |
| <FormData FieldName="NewField" FieldValue="test" /> |
| </Form> |
|</Root> |
我需要结束每个不同的FieldName属性值(在本例中为Username,FirstName,LastName和NewField)的结果集及其对应的FieldValue属性作为值.我上面给出的例子的结果如下：
FormEntryId | Username | FirstName | LastName | NewField | DateCreated ====================================================================== 1 | stevem | Steve | Mesa | NULL | 10/15/2009 ---------------------------------------------------------------------- 2 | bobs | Bob | Suggs | test | 10/16/2009
我已经找到了使用静态列完成此操作的方法
SELECT
FormEntryId,FormXML.value('/Root[1]/Form[1]/FormData[@FieldName="Username"][1]/@FieldValue','varchar(max)') AS Username,FormXML.value('/Root[1]/Form[1]/FormData[@FieldName="FirstName"][1]/@FieldValue','varchar(max)') AS FirstName,FormXML.value('/Root[1]/Form[1]/FormData[@FieldName="LastName"][1]/@FieldValue','varchar(max)') AS LastName,FormXML.value('/Root[1]/Form[1]/FormData[@FieldName="NewField"][1]/@FieldValue','varchar(max)') AS NewField,DateCreated
FROM FormEntry
解决方法
看看
this dynamic pivot以及最近的
this one – 您基本上需要能够使用SELECT DISTINCT FieldName来动态构建查询.
以下是您的特定问题的完整答案(请注意,在知道列应显示的顺序时,从不同属性生成列表时存在列顺序弱点：
DECLARE @template AS varchar(MAX)
SET @template = 'SELECT
FormEntryId,{@col_list},DateCreated
FROM FormEntry'
DECLARE @col_template AS varchar(MAX)
SET @col_template = 'FormXML.value(''/Root[1]/Form[1]/FormData[@FieldName="{FieldName}"][1]/@FieldValue'',''varchar(max)'') AS {FieldName}'
DECLARE @col_list AS varchar(MAX)
;WITH FieldNames AS (
SELECT DISTINCT FieldName
FROM FormEntry
CROSS APPLY (
SELECT X.FieldName.value('@FieldName','varchar(255)')
FROM FormXML.nodes('/Root[1]/Form[1]/FormData') AS X(FieldName)
) AS Y (FieldName)
)
SELECT @col_list = COALESCE(@col_list + ',','') + REPLACE(@col_template,'{FieldName}',FieldName)
FROM FieldNames
DECLARE @sql AS varchar(MAX)
SET @sql = REPLACE(@template,'{@col_list}',@col_list)
EXEC (@sql)
