cnblogs.com的html文件

dcrenl/SQL Server中取两个表的交集，并集和差集.html

@@ -0,0 +1,30 @@
+<p>在项目中遇到要取两个表差集的情况</p>
+<p>假设有两个表tblNZPostCodes, NZPostcode &nbsp;两个表中存储的都是新西兰的post code信息，字段一致，只是数据上有所差异。</p>
+<p>&nbsp;</p>
+<p>1. Union &nbsp;获取两个表的合集并且自动过滤重复数据</p>
+<div class="cnblogs_code">
+<pre>Select * from tblNZPostCodes
+Union
+Select * from NZPostcode</pre>
+</div>
+<p>2. Union all 获取两个表的合集并且不过滤重复数据&nbsp;</p>
+<div class="cnblogs_code">
+<pre>Select * from tblNZPostCodes
+Union all
+Select * from NZPostcode</pre>
+</div>
+<p>3. Intersect 获取两个表的交集</p>
+<div class="cnblogs_code">
+<pre>Select * from tblNZPostCodes
+intersect
+Select * from NZPostcode</pre>
+</div>
+<p>4. except 获取第1个表中存在，而第2个表中不存在的数据</p>
+<p>&nbsp; &nbsp; 比如，下面的语句将获取在tblNZPostCodes中存在，但NZPostcode中不存在的数据</p>
+<div class="cnblogs_code">
+<pre>Select * from tblNZPostCodes
+except
+Select * from NZPostcode</pre>
+</div>
+<p>&nbsp;</p>
+<p>转自：https://www.cnblogs.com/wphl-27/p/5488080.html</p>