sqlserver中distinct的用法(不重复的记录)
发布时间：2020-12-12 09:31:10 所属栏目：MsSql教程 来源：网络整理
导读：下面先来看看例子： P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px;
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下面先来看看例子： <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">字段1字段2 idname 1a 2b 3c 4c 5b <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">库结构大概这样，这只是一个简单的例子，实际情况会复杂得多。 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">比如我想用一条语句查询得到name不重复的所有数据，那就必须 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">使用distinct去掉多余的重复记录。 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">select distinct name from table 得到的结果是: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">---------- <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">name ac <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">好像达到效果了，可是，我想要得到的是id值呢？改一下查询语句吧: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">select distinct name,id from table <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">结果会是: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">---------- <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">id name 1 a 2 b 3 c 4 c 5 b <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">distinct怎么没起作用？作用是起了的，不过他同时作用了两个 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">字段，也就是必须得id与name都相同的才会被排除 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">我们再改改查询语句: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">select id,distinct name from table <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">很遗憾，除了错误信息你什么也得不到，distinct必须放在开头。难到不能把distinct放到where条件里？能，照样报错。 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">-------------------------------------------------------- <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">下面方法可行: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">select *,count(distinct name) from table group by name <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">结果: <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">id name count(distinct name) 1 a 1 2 b 1 3 c 1 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">最后一项是多余的，不用管就行了，目的达到 <P style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px 0px 5px; WORD-BREAK: normal; LINE-HEIGHT: 1.5em; PADDING-TOP: 0px; LIST-STYLE-TYPE: none; BORDER-RIGHT-WIDTH: 0px; WORD-WRAP: normal">group by 必须放在 order by 和 limit之前，不然会报错 <DIV id=c_jquery_test style="DISPLAY: none"> （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |