[英]Query XML Node Value by Node Attribute
我正在嘗試檢索作為xml數據類型存儲在sql server列中的xml節點的值。 例如,我的xml列數據是:
<fields>
<field id="StudentName">John Smith</field>
<field id="StudentID">1310021003</field>
<field id="SchoolName">Little Kid Elementary School</field>
</fields>
我想檢索StudentID。 當我在下面運行腳本時,我得到空值。
select MyColumnName.value('(/fields/field/@StudentID)[1]', 'varchar(20)') as StudentId from MyTable
[獎勵問題]-如果可能的話,我還想通過Studentid查詢表,例如: select * from MyTable where MyColumnName.value('(/fields/field/@StudentID)[1]', 'varchar(20)') = '1310021003'
首先,這將是測試環境:
declare @MyTable table (MyColumnName xml)
insert into @MyTable
select '<fields>
<field id="StudentName">John Smith</field>
<field id="StudentID">1310021003</field>
<field id="SchoolName">Little Kid Elementary School</field>
</fields>' union all
select '<fields>
<field id="StudentName">John Smith</field>
<field id="StudentID">2343343434</field>
<field id="SchoolName">Little Kid Elementary School</field>
</fields>'
要從xml獲取數據,請使用value()
函數:
select
MyColumnName.value('(fields/field[@id="StudentID"]/text())[1]', 'nvarchar(max)') as StudentID
from @MyTable
輸出:
StudentID
-----------
1310021003
2343343434
要按xml數據過濾,請使用exist()
函數
select
*
from @MyTable
where MyColumnName.exist('fields/field[@id="StudentID" and text()=1310021003]') = 1
輸出:
MyColumnName
-----------
<fields>
<field id="StudentName">John Smith</field>
<field id="StudentID">1310021003</field>
<field id="SchoolName">Little Kid Elementary School</field>
</fields>
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