为了解决在大数据查询时不使用 in 操作符，所以使用下面的方案替换 in 的使用
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--1.优化前后代码对比
优化前的代码：
select * from orderinfo where orderid in (1,2,3,4,5,........,n);
优化后的代码：
declare @xmlDoc xml;
set @xmlDoc='
<orders title="订单号">
<id>1111</id>
<id>2222</id>
<id>3333</id>
<id>4444</id>
</orders>';
select * from orderinfo
where exists
(
select 1 from @xmlDoc.nodes('/orders/id') as T(c)
where T.c.value('text()[1]','int')= orderinfo.OrderID
);
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--2.其它基础的 xquery 使用
declare @xmlDoc xml; set @xmlDoc=' <orders title="订单号"> <id>862875</id> <id>862874</id> <id>862873</id> <id>862872</id> </orders>'; --查询所有Id节点 select @xmlDoc.query('/orders/id') c1 --查询第一个Id节点值,@xmlDoc.value('(/orders/id)[1]','nvarchar(max)') AS c2 --查询最后一个Id节点值,@xmlDoc.value('(/orders/id)[last()]','nvarchar(max)') AS c3 --查找属性,@xmlDoc.value('(/orders/@title)[1]','nvarchar(max)') AS c4 --xml 与表合并查询1（推荐） select * from orderinfo where exists ( select 1 from @xmlDoc.nodes('/orders/id') as T(c) where T.c.value('text()[1]','int')= orderinfo.OrderID ); --xml 与表合并查询（和in效果一样） select * from orderinfo where OrderID in ( select T.c.value('text()[1]','int') from @xmlDoc.nodes('/orders/id') as T(c) ); ---------------------------------- --3. ADO.NET 中执行xml查询 DataTable dt = new DataTable(); using (sqlConnection conn = new sqlConnection(connectionString)) { string xml = @" <orders title="订单号"> <id>862875</id> <id>862874</id> <id>862873</id> <id>862872</id> </orders> "; sqlCommand comm = conn.CreateCommand(); comm.CommandText = @" select * from orderinfo where exists ( select 1 from @xmlDoc.nodes('/orders/id') as T(c) where T.c.value('text()[1]','int')= orderinfo.OrderID );"; comm.Parameters.Add(new sqlParameter("@xml",sqlDbType.Xml) { Value = xml }); using (sqlDataAdapter adapter = new sqlDataAdapter(comm)) { adapter.SelectCommand = comm; adapter.Fill(dt); } } 原文链接：https://www.f2er.com/xml/298867.html