<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[ctmedia的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/ctmedia</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; ctmedia]]></copyright><item><title><![CDATA[SQL查询语句-汇总分析]]></title><link>https://blog.youkuaiyun.com/ctmedia/article/details/136378800</link><guid>https://blog.youkuaiyun.com/ctmedia/article/details/136378800</guid><author>ctmedia</author><pubDate>Thu, 29 Feb 2024 19:11:30 +0800</pubDate><description><![CDATA[求某列数据删除重复值后的行数select count(distince 姓名) from student。列名 (not) in ( )：查询结果是括号里的内容返回值1，排在后面；否则返回值0，排在前面。错误1：在分组条件having中使用了查询结果select里的别名。错误3：在创建表时把数值数据设置成字符串数值。错误2：在行条件where后使用了汇总函数。]]></description><category></category></item></channel></rss>