在SQL Server中连接XML变量

我在存储过程中有一个查询，检索一些XML格式的数据，以变量@XML_data返回，如下所示：

SELECT @xml_data = (
    SELECT * FROM (
        SELECT   1 AS Tag
                ,0 AS Parent
                .....
        FROM    MyTable
        WHERE   id = @id

        UNION ALL

        SELECT   2 AS Tag
                ,1 AS Parent
                ....
        FROM    MyTable2
        WHERE   id = @id

        UNION ALL

        SELECT   3 AS Tag
                ,2 AS Parent
                ....
        FROM    MyTable3
        WHERE   id = @id
    ) results
FOR XML EXPLICIT, TYPE)

这就像众所周知的梦想：

但是，我想将一个头连接到这个XML，例如，但不知道如何做。我试着转换成NVARCHAR，在一个语句中选择两个变量，但似乎无法正确实现

有人能帮忙吗

谢谢：

试着这样做：

DECLARE @x xml 
DECLARE @strXML varchar(MAX)
SET @x=N'<Employee><Name>Luftwaffe</Name></Employee>'
set @strXML = '<xml version="1.0" encoding="ISO-8859-1"/>' + CONVERT(varchar(MAX),@x)
SELECT @strXML  

---

希望有帮助

您只需在开头声明字符串并将它们连接在一起：

declare @xml_data nvarchar(MAX)

set @xml_data = '<xml version="1.0" encoding="ISO-8859-1"/>'

SELECT @xml_data = @xml_data +  (
    SELECT * FROM (
        SELECT   1 AS Tag
                ,0 AS Parent
                .....
        FROM    MyTable
        WHERE   id = @id

        UNION ALL

        SELECT   2 AS Tag
                ,1 AS Parent
                ....
        FROM    MyTable2
        WHERE   id = @id

        UNION ALL

        SELECT   3 AS Tag
                ,2 AS Parent
                ....
        FROM    MyTable3
        WHERE   id = @id
    ) results
FOR XML EXPLICIT, TYPE)