sql - 如何在 SQL Server 的存储过程中从 xml 节点创建游标？

Question

我将一个 XML 文档作为参数传递到我的存储过程。然后我试图填充游标以循环遍历 XML 的元素。我的问题是如何选择此 XML 文档的每个元素并用它们填充我的光标？

XML 文档

<Authors>
    <Author_id>1</Author_id>
    <Author_id>2</Author_id>
</Authors>

存储过程

CREATE PROCEDURE Insert_Publication
    @authors xml
AS

    DECLARE @id int

    DECLARE authors_cursor CURSOR FOR
    SELECT @authors.query('(/Authors/Author_id)') 

    open authors_cursor 

    FETCH NEXT FROM authors_cursor INTO @id

Answer 1

您可以使用 .nodes()和 .value() :

DECLARE @authors XML = 
'<Authors>
    <Author_id>1</Author_id>
    <Author_id>2</Author_id>
</Authors>';

DECLARE @id INT;

DECLARE authors_cursor CURSOR FOR
SELECT n.c.value('.', 'INT') AS author_id
FROM @authors.nodes('/Authors/Author_id') AS n(c);

OPEN authors_cursor;

FETCH NEXT FROM authors_cursor INTO @id;

WHILE @@FETCH_STATUS = 0
BEGIN
  PRINT @id;                                -- do whatever you need with @id
  FETCH NEXT FROM authors_cursor INTO @id;
END

CLOSE authors_cursor;
DEALLOCATE authors_cursor; 

LiveDemo

工作原理:

DECLARE authors_cursor CURSOR FOR
SELECT n.c.value('.', 'INT') AS author_id
FROM @authors.nodes('/Authors/Author_id') AS n(c);

1. @authors.nodes('/Authors/Author_id') 获取基于 XQuery 的节点和派生表的别名 n 和 c - 用于列

2. 使用n.c.value('.', 'INT') AS author_id获取元素的实际值