SQL中的XML：当使用表列而不是字符串时，元素值的计算方式不同

Question

我试图通过SQL为负载测试生成一些XML，但我在正确构建XML时遇到了问题。这是我有：

-- Generate XML from table 
SELECT id AS '@id', 
action AS '@action', 
actionTime AS '@actionTime', 
firstName AS '@firstName', 
lastName AS '@lastName', 
email AS '@email', 
    (SELECT isActive AS '@isActive', 
    actionTime AS '@actionTime', 
    displayName AS '@displayName', 
    identifierId 
FOR XML PATH('identifier'), TYPE 
) 
FROM scratch.dbo.Identities 
FOR XML PATH('user'), ROOT('Users') 

这会生成XML，看起来像这样：

<Users> 
    <user id="QALoadTest1" action="add" actionTime="2015-11-01T00:00:00" firstName="Load" lastName="Test1" email="QALoadTest1@loadtest.com"> 
    <identifier isActive="1" actionTime="2015-11-01T00:00:00" displayName="Load Test 1"> 
     <identifierId>1111111111</identifierId> 
     </identifier> 
    </user> 
</Users> 

如果我传递一个字符串作为标识符值，正确生成XML：

SELECT id AS '@id', 
action AS '@action', 
actionTime AS '@actionTime', 
firstName AS '@firstName', 
lastName AS '@lastName', 
email AS '@email', 
    (SELECT isActive AS '@isActive', 
    actionTime AS '@actionTime', 
    displayName AS '@displayName', 
    '11111111111' 
FOR XML PATH('identifier'), TYPE 
) 
FROM scratch.dbo.Identities 
FOR XML PATH('user'), ROOT('Users') 

这将生成以下，这正是我想要的：

<Users> 
    <user id="QALoadTest1" action="add" actionTime="2015-11-01T00:00:00" firstName="Load" lastName="Test1" email="QALoadTest1@loadtest.com"> 
    <identifier isActive="1" actionTime="2015-11-01T00:00:00" displayName="Load Test 1">11111111111</identifierId> 
    </user> 
</Users> 

在这里使用列值和字符串有什么区别？有趣的是，当我将列值换成单引号（''' + identifierId + '''）时，它会生成正确结构的XML，但带有额外的引号（...displayName="Load Test 1">'11111111111'</identifierId>）

Answer 1

您的硬编码值不会自动生成列名称;列选择不（看看SELECT identifierId from Identities和SELECT '11111111111' from Identities的结果的标题中的差异。）

试着告诉它，你特别想在一个文本节点，而不是一列衍生名您的数据：

-- Generate XML from table 
SELECT id AS '@id', 
action AS '@action', 
actionTime AS '@actionTime', 
firstName AS '@firstName', 
lastName AS '@lastName', 
email AS '@email', 
    (SELECT isActive AS '@isActive', 
    actionTime AS '@actionTime', 
    displayName AS '@displayName', 
    identifierId AS 'text()' 
FOR XML PATH('identifier'), TYPE 
) 
FROM scratch.dbo.Identities 
FOR XML PATH('user'), ROOT('Users')