获取XML字段中的节点数XQuery SQL Server 2008

Question

我正在尝试获取XML字段中的节点数。但我总是看到0作为结果。这是我的查询的样子。

DECLARE @XmlTable TABLE (XmlResult XML) 
INSERT INTO @XmlTable EXECUTE [dbo].usp_GetBooks @EditionId=400 
--select * from @XmlTable 
SELECT 
--Count number of nodes 
    COUNT(*) AS BooksCount 
FROM 
(
SELECT XmlResult FROM @XmlTable 
) AS XmlTable(XmlColumn) 
CROSS APPLY XmlColumn.nodes('./books/book') XmlTableFunction(XmlColumn2); 

我的XML看起来像：

<Version number ="1"> 
<books> 
<book> 
    <name> </name> 
    <author></author> 
</book> 
<book> 
    <name> </name> 
    <author></author> 
</book> 
</books> 
</Version> 

Answer 1

我觉得你的XPath表达式是错误的 - 试试这个：

DECLARE @XmlTable TABLE (XmlResult XML) 

INSERT INTO @XmlTable EXECUTE [dbo].usp_GetBooks @EditionId=400 

SELECT 
    COUNT(*) AS BooksCount 
FROM 
    (SELECT XmlResult FROM @XmlTable) AS XmlTable(XmlColumn) 
CROSS APPLY 
    XmlColumn.nodes('/Version/books/book') XmlTableFunction(XmlColumn2) 

或者更简单：

DECLARE @XmlTable TABLE (XmlResult XML) 

INSERT INTO @XmlTable EXECUTE [dbo].usp_GetBooks @EditionId=400 

SELECT 
    XmlResult.value('count(/Version/books/book)', 'int') 
FROM 
    @XmlTable 

Answer 2

与XML模式对我的作品你给

DECLARE @XmlTable TABLE (XmlResult XML) 
INSERT INTO @XmlTable VALUES ('<books><book><title>GWTW</title></book></books>') 
INSERT INTO @XmlTable VALUES ('<foo />') 
INSERT INTO @XmlTable VALUES ('<books />') 
SELECT 
    COUNT(*) AS BooksCount 
FROM 
(
SELECT XmlResult FROM @XmlTable 
) AS XmlTable(XmlColumn) 
CROSS APPLY XmlColumn.nodes('./books/book') XmlTableFunction(XmlColumn2); 

存在的方法是非常有用的。我使用NULLIF改变0为NULL（这是一点，所以需要与CAST SUM）

SELECT COUNT(NULLIF(XmlResult.exist('./books/book'), 0)) FROM @XmlTable 

编辑，更新

您发布的XML是错的太多了。

你是不是正确，指定根音：

DECLARE @XmlTable TABLE (XmlResult XML) 
INSERT INTO @XmlTable VALUES (' 
<Version number ="1"> 
<books> 
<book> 
    <name> </name> 
    <author></author> 
</book> 
<book> 
    <name> </name> 
    <author></author> 
</book> 
</books> 
</Version>') 
SELECT 
    COUNT(*) 
FROM 
(
SELECT XmlResult FROM @XmlTable 
) AS XmlTable(XmlColumn) 
CROSS APPLY XmlColumn.nodes('/Version/books/book') XmlTableFunction(XmlColumn2); 

SELECT 
    COUNT(*) 
FROM 
(
SELECT XmlResult FROM @XmlTable 
) AS XmlTable(XmlColumn) 
CROSS APPLY XmlColumn.nodes('*/books/book') XmlTableFunction(XmlColumn2);