blocks|key|4234274|text|请尝试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4234275|select+
+MAX(id)+id,+
+classname+
from(
+++++select+*+from+table1+union
+++++select+*+from+table2
)x+group+by+classname|code-block|syntax|javascript|4234276|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Please try:

<pre><code>select 
 MAX(id) id, 
 classname 
from(
 select * from table1 union
 select * from table2
)x group by classname
</code></pre>

blocks|key|1560683|text|您可以使用以下命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1560684|select+distinct+id,
++++(select+top+1+classname+from+table1+t2+where+t2.id+=+t.id+order+by+case+classname+when+'unknown'+then+0+else+1+end)+classname
from+Table1+t|code-block|syntax|javascript|1560685|我不确定您希望将哪个副本作为classname返回。您可以通过在内部查询中更改order+by来控制id。|offset|length|style|CODE|1560686|如果你想完全删除未知的东西|1560687|select+distinct+id,
++++(select+top+1+classname+from+table1+t2+where+t2.id+=+t.id+and+t2.classname+<>+'unknown')+classname
from+Table1+t
++++where+t.classname+<>+'unknown'|1560688|entityMap^0|0|0|E|9|13|8|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]|$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

You can use this:

<pre><code>select distinct id,
 (select top 1 classname from table1 t2 where t2.id = t.id order by case classname when 'unknown' then 0 else 1 end) classname
from Table1 t
</code></pre>

I wasn't sure which of the duplicates you want to return as <code>classname</code>. You can control id by changing <code>order by</code> in the inner query.

If you want to completely remove unknowns

<pre><code>select distinct id,
 (select top 1 classname from table1 t2 where t2.id = t.id and t2.classname &lt;&gt; 'unknown') classname
from Table1 t
 where t.classname &lt;&gt; 'unknown'
</code></pre>

blocks|key|1555608|text|根据您对Szymon的回答的评论，尝试以下查询：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555609|++++select+distinct+id,
(select+top+1+classname+from+table1+t2+where+t2.id+=+t.id+and+classname!='unknown'+order+by+case+classname+when+'unknown'+then+0+else+1+end)+classname
from+Table1+t+|code-block|syntax|javascript|1555610|正如您所要求的：：您不希望获取具有“未知”名称的类。|1555611|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

As per your comment on Szymon's answer try the below query:

<pre><code> select distinct id,
(select top 1 classname from table1 t2 where t2.id = t.id and classname!='unknown' order by case classname when 'unknown' then 0 else 1 end) classname
from Table1 t 
</code></pre>

as you required:: you don't want to get the class with 'unknow' name.

blocks|key|1560718|text|这对我很有效|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1560719|select+*+into+#tbl+from(
select+123+id+,'class1'+classname
union+select+123,'unknown'
union+select+124,'class2'
union+select+125,'unknown'
)+A

select+*+from+#tbl

select+MAX(ID),classname+
from+#tbl+
group+by+classname

drop+table+#tbl|code-block|syntax|javascript|1560720|这将得到与您在问题中显示的结果相同的结果。但我担心的是MAX(+ID+)，因为它只给出了classname的重复条目的larget+ID。因此，请根据您的需要进行选择。|1560721|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This worked for me 

<pre><code>select * into #tbl from(
select 123 id ,'class1' classname
union select 123,'unknown'
union select 124,'class2'
union select 125,'unknown'
) A

select * from #tbl

select MAX(ID),classname 
from #tbl 
group by classname

drop table #tbl
</code></pre>

This gets the same result as you have shown in the question. But I am concerned about MAX(ID) because it only give the larget ID of the duplicate entries of classname. So choose accordingly to your needs.

i have table where i have a duplicate records with different coulmn names 
for eg 

<pre><code>id classname
123 class1
123 unknown 
</code></pre>

then i also have some tags with only unique class name 
fr eg 

<pre><code>id classname
124 class2 
125 unknown 
</code></pre>

so now i run a select query i get result 

<pre><code>id classname
123 class1
123 unknown
124 class2
125 unknown 
</code></pre>

i want to return values in such a way that one of the duplicates is selected 

<pre><code>id classnae
123 class1 
124 class2 
125 unknown
</code></pre>

the above mentione is what i have to get as result .
I was using left outer join to write this .

<pre><code>select t.id,t.classname from Table1 t 
left outer join 
(select id,classname from Table1 GROUP BY id
 HAVING COUNT(id) &gt; 1 ) 
s on s.Tagname = t.TagName 
</code></pre>

but i am getting the same no of records that i used to get earlier with duplicates.

need help to write this

how to return one of the duplicates from the table

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个表，其中我有一个重复的记录，具有不同的名称，例如id  classname123 class1123 unknown 然后我也有一些只有唯一类名的标签，例如id  classname124  class2 125  unknown 所以现在我运行select查询，得到结果id  classname123 cla...

问如何返回表中的一个重复项
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问如何返回表中的一个重复项EN