�??xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/"><channel><title>&#22269;&#20135;&#31934;&#21697;&#20037;&#20037;&#20037;&#20037;&#39640;&#28526;&#44;&#20122;&#27954;&#25104;&#20154;&#31934;&#21697;&#19968;&#21306;&#44;&#20122;&#27954;&#26368;&#26032;&#97;&#118;</title><link>http://www.aygfsteel.com/zlsunnan/category/5587.html</link><description>世界��L��反反覆覆错错落落地飘�?来不及叹�?生活不是�q�_�^淡��E从从容容的东�?不能攑ּ�</description><language>zh-cn</language><lastBuildDate>Wed, 28 Feb 2007 03:25:23 GMT</lastBuildDate><pubDate>Wed, 28 Feb 2007 03:25:23 GMT</pubDate><ttl>60</ttl><item><title>SQL Server日期计算</title><link>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22496.html</link><dc:creator>☆蓝色梦想☆</dc:creator><author>☆蓝色梦想☆</author><pubDate>Mon, 05 Dec 2005 01:25:00 GMT</pubDate><guid>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22496.html</guid><wfw:comment>http://www.aygfsteel.com/zlsunnan/comments/22496.html</wfw:comment><comments>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22496.html#Feedback</comments><slash:comments>0</slash:comments><wfw:commentRss>http://www.aygfsteel.com/zlsunnan/comments/commentRss/22496.html</wfw:commentRss><trackback:ping>http://www.aygfsteel.com/zlsunnan/services/trackbacks/22496.html</trackback:ping><description><![CDATA[<P>通常�Q�你需要获得当前日期和计算一些其他的日期�Q�例如，你的�E�序可能需要判断一个月的第一天或者最后一天。你们大部分人大概都知道怎样把日期进行分�Ԍ���q�、月、日�{�）�Q�然后仅仅用分割出来的年、月、日�{�放在几个函��C��计算�����己所需要的日期�Q�在�q�篇文章里，我将告诉你如何��用DATEADD和DATEDIFF函数来计���出在你的程序中可能你要用到的一些不同日期�?nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 在��用本文中的例子之前，你必���L��意以下的问题。大部分可能不是所有例子在不同的机器上执行的结果可能不一��P���q�完全由哪一天是一个星期的�W�一天这个设�|�决定。第一天（DATEFIRST�Q�设定决定了你的�pȝ��使用哪一天作��Z��周的�W�一天。所有以下的例子都是以星期天作�ؓ一周的�W�一天来建立�Q�也���是�W�一天设�|��ؓ7。假如你的第一天设�|�不一��P��你可能需要调整这些例子，使它和不同的�W�一天设�|�相�W�合。你可以通过@@DATEFIRST函数来检查第一天设�|��?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ��Z��理解�q�些例子�Q�我们先复习一下DATEDIFF和DATEADD函数。DATEDIFF函数计算两个日期之间的小时、天、周、月、年�{�时间间隔��L��。DATEADD函数计算一个日期通过�l�时间间隔加减来获得一个新的日期。要了解更多的DATEDIFF和DATEADD函数以及旉���间隔可以阅读微��Y联机帮助�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 使用DATEDIFF和DATEADD函数来计���日期，和本来从当前日期转换��C��需要的日期的考虑�Ҏ��有点不同。你必须从时间间隔这个方面来考虑。比如，从当前日期到你要得到的日期之间有多少旉���间隔�Q�或者，从今天到某一天（比如1900-1-1�Q�之间有多少旉���间隔�Q�等�{�。理解怎样着��g��旉���间隔有助于你��L��的理解我的不同的日期计算例子�?nbsp; <BR>&nbsp;<BR>一个月的第一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �W�一个例子，我将告诉你如何从当前日期去这个月的最后一天。请注意�Q�这个例子以及这���文章中的其他例子都���只使用DATEDIFF和DATEADD函数来计���我们想要的日期。每一个例子都���通过计算但前的时间间隔，然后�q�行加减来得到想要计���的日期�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�是计算一个月�W�一天的SQL&nbsp; 脚本�Q?nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; DATEADD(mm,&nbsp; DATEDIFF(mm,0,getdate()),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 我们把这个语句分开来看看它是如何工作的。最核心的函数是getdate()�Q�大部分人都知道�q�个是返回当前的日期和时间的函数。下一个执行的函数DATEDIFF(mm,0,getdate())是计���当前日期和�?900-01-01&nbsp; 00:00:00.000”这个日期之间的月数。记住：时期和时间变量和毫秒一��h��从�?900-01-01&nbsp; 00:00:00.000”开始计���的。这���是��Z��么你可以在DATEDIFF函数中指定第一个时间表辑ּ�为�?”。下一个函数是DATEADD�Q�增加当前日期到�?900-01-01”的月数。通过增加预定义的日期�?900-01-01”和当前日期的月敎ͼ�我们可以获得�q�个月的�W�一天。另外，计算出来的日期的旉���部分���会是�?0:00:00.000”�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�个计算的技巧是先计���当前日期到�?900-01-01”的旉���间隔敎ͼ�然后把它加到�?900-01-01”上来获得特�D�的日期�Q�这个技巧可以用来计���很多不同的日期。下一个例子也是用�q�个技巧从当前日期来��生不同的日期�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp; <BR>本周的星期一&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�里我是用周(wk)的时间间隔来计算哪一天是本周的星期一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; DATEADD(wk,&nbsp; DATEDIFF(wk,0,getdate()),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>一�q�的�W�一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 现在用年(yy)的时间间隔来昄����q�一�q�的�W�一天�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; DATEADD(yy,&nbsp; DATEDIFF(yy,0,getdate()),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>季度的第一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 假如你要计算�q�个季度的第一天，�q�个例子告诉你该如何做�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; DATEADD(qq,&nbsp; DATEDIFF(qq,0,getdate()),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>当天的半�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 曄���需要通过getdate()函数��Z���q�回旉���值截掉时间部分，��׃��考虑到当前日期是不是在半夜。假如这��P���q�个例子使用DATEDIFF和DATEADD函数来获得半夜的旉���炏V�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; DATEADD(dd,&nbsp; DATEDIFF(dd,0,getdate()),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>深入DATEDIFF和DATEADD函数计算&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 你可以明白，通过使用���单的DATEDIFF和DATEADD函数计算�Q�你可以发现很多不同的可能有意义的日期�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 目前为止的所有例子只是仅仅计���当前的旉���和�?900-01-01”之间的旉���间隔数量�Q�然后把它加到�?900-01-01”的旉���间隔上来计算出日期。假定你修改旉���间隔的数量，或者��用不同的旉���间隔来调用DATEADD函数�Q�或者减��L��间间隔而不是增加，那么通过�q�些���的调整你可以发现和多不同的日期�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�里有四个例子��用另外一个DATEADD函数来计���最后一天来分别替换DATEADD函数前后两个旉���间隔�?nbsp; <BR>&nbsp;<BR>上个月的最后一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�是一个计���上个月最后一天的例子。它通过从一个月的最后一天这个例子上减去3毫秒来获得。有一点要��C���Q�在Sql&nbsp; Server中时间是�_�����?毫秒。这���是��Z��么我需要减�?毫秒来获得我要的日期和时间�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; dateadd(ms,-3,DATEADD(mm,&nbsp; DATEDIFF(mm,0,getdate()),&nbsp; 0))&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 计算出来的日期的旉���部分包含了一个Sql&nbsp; Server可以记录的一天的最后时�?�?3:59:59:997�?的时间�?nbsp; <BR>&nbsp;<BR>��d��的最后一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; �q�接上面的例子，��Z��要得到去�q�的最后一天，你需要在今年的第一天上减去3毫秒�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; dateadd(ms,-3,DATEADD(yy,&nbsp; DATEDIFF(yy,0,getdate()),&nbsp; 0))&nbsp; <BR>&nbsp;<BR>本月的最后一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 现在�Q��ؓ了获得本月的最后一天，我需要稍微修改一下获得上个月的最后一天的语句。修攚w��要给用DATEDIFF比较当前日期和�?900-01-01”返回的旉���间隔上加1。通过�?个月�Q�我计算��Z��个月的第一天，然后减去3毫秒�Q�这样就计算��Z���q�个月的最后一天。这是计���本月最后一天的SQL脚本�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; dateadd(ms,-3,DATEADD(mm,&nbsp; DATEDIFF(m,0,getdate())+1,&nbsp; 0))&nbsp; <BR>&nbsp;<BR>本年的最后一�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 你现在应该掌握这个的做法�Q�这是计���本�q�最后一天脚�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SELECT&nbsp; dateadd(ms,-3,DATEADD(yy,&nbsp; DATEDIFF(yy,0,getdate())+1,&nbsp; 0))�?nbsp; <BR>&nbsp;<BR>本月的第一个星期一&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 好了�Q�现在是最后一个例子。这里我要计���这个月的第一个星期一。这是计���的脚本�?nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; select&nbsp; DATEADD(wk,&nbsp; DATEDIFF(wk,0,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dateadd(dd,6-datepart(day,getdate()),getdate())&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ),&nbsp; 0)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 在这个例子里�Q�我使用了“本周的星期一”的脚本�Q��ƈ作了一点点修改。修改的部分是把原来脚本中“getdate()”部分替换成计算本月的第6天，在计���中用本月的�W?天来替换当前日期使得计算可以获得�q�个月的�W�一个星期一�?nbsp; <BR>&nbsp;<BR>�ȝ��&nbsp; <BR>&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 我希望这些例子可以在你用DATEADD和DATEDIFF函数计算日期时给你一点启发。通过使用�q�个计算日期的时间间隔的数学�Ҏ���Q�我发现��Z��昄���两个日期之间间隔的有用历法是有�h值的。注意，�q�只是计���出�q�些日期的一�U�方法。要牢记�Q�还有很多方法可以得到相同的计算�l�果。假如你有其他的�Ҏ���Q�那很不错，要是你没有，我希望这些例子可以给你一些启发，当你要用DATEADD和DATEDIFF函数计算你程序可能要用到的日期时�?nbsp; <BR>&nbsp;<BR>---------------------------------------------------------------&nbsp; <BR>附录�Q�其他日期处理方�?nbsp; <BR>&nbsp;<BR>1)��L��时分�U?nbsp; <BR>declare&nbsp; @&nbsp; datetime&nbsp; <BR>set&nbsp; @&nbsp; =&nbsp; getdate()&nbsp; --'2003-7-1&nbsp; 10:00:00'&nbsp; <BR>SELECT&nbsp; @,DATEADD(day,&nbsp; DATEDIFF(day,0,@),&nbsp; 0)&nbsp; <BR>&nbsp;<BR>2�Q�显�C�星期几&nbsp; <BR>select&nbsp; datename(weekday,getdate())&nbsp;&nbsp;&nbsp; <BR>&nbsp;<BR>3�Q�如何取得某个月的天�?nbsp; <BR>declare&nbsp; @m&nbsp; int&nbsp; <BR>set&nbsp; @m=2&nbsp; --月䆾&nbsp; <BR>select&nbsp;&nbsp;&nbsp; datediff(day,'2003-'+cast(@m&nbsp; as&nbsp; varchar)+'-15'&nbsp; ,'2003-'+cast(@m+1&nbsp;&nbsp;&nbsp; as&nbsp; varchar)+'-15')&nbsp; <BR>另外�Q�取得本月天�?nbsp; <BR>select&nbsp;&nbsp;&nbsp; datediff(day,cast(month(GetDate())&nbsp; as&nbsp; varchar)+'-'+cast(month(GetDate())&nbsp; as&nbsp; varchar)+'-15'&nbsp; ,cast(month(GetDate())&nbsp; as&nbsp; varchar)+'-'+cast(month(GetDate())+1&nbsp;&nbsp;&nbsp; as&nbsp; varchar)+'-15')&nbsp; <BR>或者��用计���本月的最后一天的脚本�Q�然后用DAY函数区最后一�?nbsp; <BR>SELECT&nbsp; Day(dateadd(ms,-3,DATEADD(mm,&nbsp; DATEDIFF(m,0,getdate())+1,&nbsp; 0)))&nbsp; <BR>&nbsp;<BR>4�Q�判断是否闰�q�_��&nbsp; <BR>SELECT&nbsp; case&nbsp; day(dateadd(mm,&nbsp; 2,&nbsp; dateadd(ms,-3,DATEADD(yy,&nbsp; DATEDIFF(yy,0,getdate()),&nbsp; 0))))&nbsp; when&nbsp; 28&nbsp; then&nbsp; '�q�_��'&nbsp; else&nbsp; '闰年'&nbsp; end&nbsp; <BR>或�?nbsp; <BR>select&nbsp; case&nbsp; datediff(day,datename(year,getdate())+'-02-01',dateadd(mm,1,datename(year,getdate())+'-02-01'))&nbsp; <BR>when&nbsp; 28&nbsp; then&nbsp; '�q�_��'&nbsp; else&nbsp; '闰年'&nbsp; end&nbsp; <BR>&nbsp;<BR>5�Q�一个季度多���天&nbsp; <BR>declare&nbsp; @m&nbsp; tinyint,@time&nbsp; smalldatetime&nbsp; <BR>select&nbsp; @m=month(getdate())&nbsp; <BR>select&nbsp; @m=case&nbsp; when&nbsp; @m&nbsp; between&nbsp; 1&nbsp; and&nbsp; 3&nbsp; then&nbsp; 1&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; when&nbsp; @m&nbsp; between&nbsp; 4&nbsp; and&nbsp; 6&nbsp; then&nbsp; 4&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; when&nbsp; @m&nbsp; between&nbsp; 7&nbsp; and&nbsp; 9&nbsp; then&nbsp; 7&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; else&nbsp; 10&nbsp; end&nbsp; <BR>select&nbsp; @time=datename(year,getdate())+'-'+convert(varchar(10),@m)+'-01'&nbsp; <BR>select&nbsp; datediff(day,@time,dateadd(mm,3,@time))&nbsp; </P><img src ="http://www.aygfsteel.com/zlsunnan/aggbug/22496.html" width = "1" height = "1" /><br><br><div align=right><a style="text-decoration:none;" href="http://www.aygfsteel.com/zlsunnan/" target="_blank">☆蓝色梦想☆</a> 2005-12-05 09:25 <a href="http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22496.html#Feedback" target="_blank" style="text-decoration:none;">发表评论</a></div>]]></description></item><item><title>察看重复的记�?/title><link>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22495.html</link><dc:creator>☆蓝色梦想☆</dc:creator><author>☆蓝色梦想☆</author><pubDate>Mon, 05 Dec 2005 01:24:00 GMT</pubDate><guid>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22495.html</guid><wfw:comment>http://www.aygfsteel.com/zlsunnan/comments/22495.html</wfw:comment><comments>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22495.html#Feedback</comments><slash:comments>0</slash:comments><wfw:commentRss>http://www.aygfsteel.com/zlsunnan/comments/commentRss/22495.html</wfw:commentRss><trackback:ping>http://www.aygfsteel.com/zlsunnan/services/trackbacks/22495.html</trackback:ping><description><![CDATA[<P>用distinct关键字可以忽略重复的记录�Q?/P>
<P>要查看重复的记录�Q�可�?/P>
<P>&nbsp;select Adminno,count(*) from admin group by Adminno having count(*)&gt;1</P>
<P>HAVING 子句�?GROUP BY 子句讄���条�g的方式与 WHERE 子句�?SELECT 语句交互的方式类伹{��WHERE 子句搜烦条�g在进行分�l�操作之前应用；�?HAVING 搜烦条�g在进行分�l�操作之后应用。HAVING 语法�?WHERE 语法�c�M���Q�但 HAVING 可以包含聚合函数。HAVING 子句可以引用选择列表中出现的��L����V�?/P><img src ="http://www.aygfsteel.com/zlsunnan/aggbug/22495.html" width = "1" height = "1" /><br><br><div align=right><a style="text-decoration:none;" href="http://www.aygfsteel.com/zlsunnan/" target="_blank">☆蓝色梦想☆</a> 2005-12-05 09:24 <a href="http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22495.html#Feedback" target="_blank" style="text-decoration:none;">发表评论</a></div>]]></description></item><item><title>查找一个表中有的而另一个表中没有的�?/title><link>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22494.html</link><dc:creator>☆蓝色梦想☆</dc:creator><author>☆蓝色梦想☆</author><pubDate>Mon, 05 Dec 2005 01:23:00 GMT</pubDate><guid>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22494.html</guid><wfw:comment>http://www.aygfsteel.com/zlsunnan/comments/22494.html</wfw:comment><comments>http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22494.html#Feedback</comments><slash:comments>0</slash:comments><wfw:commentRss>http://www.aygfsteel.com/zlsunnan/comments/commentRss/22494.html</wfw:commentRss><trackback:ping>http://www.aygfsteel.com/zlsunnan/services/trackbacks/22494.html</trackback:ping><description><![CDATA[select * from admin<BR>where id <FONT color=#d54d2b>not in</FONT> (select id from item)<img src ="http://www.aygfsteel.com/zlsunnan/aggbug/22494.html" width = "1" height = "1" /><br><br><div align=right><a style="text-decoration:none;" href="http://www.aygfsteel.com/zlsunnan/" target="_blank">☆蓝色梦想☆</a> 2005-12-05 09:23 <a href="http://www.aygfsteel.com/zlsunnan/archive/2005/12/05/22494.html#Feedback" target="_blank" style="text-decoration:none;">发表评论</a></div>]]></description></item></channel></rss>                                                                     <footer>
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