初始化XML变量

Question

DECLARE @XML1 XML 

SET @XML1=SELECT XMLCOLUMN FROM TABLE WHERE ID='123-456' 

当我做这样的我收到以下错误信息：

关键字附近有语法错误“SELECT”。

任何人都可以请帮助我如何将xmlcolumn值分配给xml变量。

Answer 1

使用

SELECT @XML1= XMLCOLUMN FROM TABLE WHERE ID='123-456' 

或者

SET @XML1= (SELECT XMLCOLUMN FROM TABLE WHERE ID='123-456') 

它们具有相同的行为，如果该查询返回的具体哪一行，但不同的除外。

+----+-------------------------------------------------------+------------------------------------------+ 
| |      SELECT       |     SET     | 
+----+-------------------------------------------------------+------------------------------------------+ 
| 0 | No Assignment made. Variable has original value.  | Variable set to null      | 
| 1 | Variable assigned the one matching value    | Variable assigned the one matching value | 
| >1 | Variable assigned arbitrary value from matching rows. | Error raised        | 
+----+-------------------------------------------------------+------------------------------------------+