SQL中的XML：當使用表列而不是字符串時，元素值的計算方式不同

Question

我試圖通過SQL爲負載測試生成一些XML，但我在正確構建XML時遇到了問題。這是我有：

-- 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') 

這會生成XML，看起來像這樣：

<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> 

如果我傳遞一個字符串作爲標識符值，正確生成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') 

這將生成以下，這正是我想要的：

<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> 

在這裏使用列值和字符串有什麼區別？有趣的是，當我將列值換成單引號（''' + identifierId + '''）時，它會生成正確結構的XML，但帶有額外的引號（...displayName="Load Test 1">'11111111111'</identifierId>）

Answer 1

您的硬編碼值不會自動生成列名稱;列選擇不（看看SELECT identifierId from Identities和SELECT '11111111111' from Identities的結果的標題中的差異。）

試着告訴它，你特別想在一個文本節點，而不是一列衍生名您的數據：

-- 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')