Question

我正在尝试检索在sql server列中存储为xml数据类型的xml节点的值。例如，我的xml列数据是：

<fields>
<field id="StudentName">John Smith</field>
<field id="StudentID">1310021003</field>
<field id="SchoolName">Little Kid Elementary School</field>
</fields>

我想检索StudentID。当我运行下面的脚本时，我得到null。

select MyColumnName.value('(/fields/field/@StudentID)[1]', 'varchar(20)') as StudentId from MyTable

[红利问题] - 如果可能，我还想通过studentid查询表格，例如：select * from MyTable where MyColumnName.value('(/fields/field/@StudentID)[1]', 'varchar(20)') = '1310021003'

Answer 1

首先，这将是测试环境：

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>'

要从xml获取数据，请使用value()函数：

select
    MyColumnName.value('(fields/field[@id="StudentID"]/text())[1]', 'nvarchar(max)') as StudentID
from @MyTable

输出：

StudentID
-----------
1310021003
2343343434

要按xml数据过滤，请使用exist()函数

select
    *
from @MyTable
where MyColumnName.exist('fields/field[@id="StudentID" and text()=1310021003]') = 1

输出：

MyColumnName
-----------
<fields>
    <field id="StudentName">John Smith</field>
    <field id="StudentID">1310021003</field>
    <field id="SchoolName">Little Kid Elementary School</field>
</fields>

按节点属性查询XML节点值

1 个答案: