SQL Server：检索列中的重复值
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SQL Server: Retrieve the duplicate value in a column
提问by Ricky
How could I filter out the duplicate value in a column with SQL syntax?
如何使用 SQL 语法过滤掉列中的重复值？
Thanks.
谢谢。
回答by Mead
A common question, though filtering out suggests you want to ignore the duplicate ones? If so, listing unique values:
一个常见的问题，尽管过滤掉表明您想忽略重复的？如果是这样，请列出唯一值：
SELECT col
FROM table
GROUP BY col
HAVING (COUNT(col) =1 )
If you just want to filter so you are left withthe duplicates
如果你只是想过滤所以你会留下重复的
SELECT col, COUNT(col) AS dup_count
FROM table
GROUP BY col
HAVING (COUNT(col) > 1)
Used www.mximize.com/how-to-find-duplicate-values-in-a-table- as a base in 2009; website content has now gone (2014).
2009 年使用 www.mximize.com/how-to-find-duplicate-values-in-a-table- 作为基础；网站内容现已消失（2014 年）。
回答by adatapost
Use DISTINCTor GROUP BY** clause.
使用DISTINCT或 GROUP BY** 子句。
Select DISTINCT City from TableName
OR
Select City from TableName GROUP BY City
回答by Filip Ekberg
Depending on how you mean "filter" you could either use DISTINCTor maybe GROUPBY both are used to Remove or Group duplicate entries.
根据您的意思“过滤器”，您可以使用DISTINCT或GROUPBY 两者都用于删除或分组重复条目。
Check the links for more information.
检查链接以获取更多信息。
A snippet from the DISTINCT-link above:
上面 DISTINCT 链接中的一个片段：
SELECT DISTINCT od.productid
FROM [order details] OD
SELECT od.productid
FROM [order details] OD
GROUP BY od.productid
Both of these generally result in the same output.
这两者通常会产生相同的输出。
回答by James Ball
You askedfor a list of the duplicates. Here is a simple way using the except operator (SQL 2008 +).
您要求提供重复项列表。这是使用except运算符的简单方法（SQL 2008+）。
select [column] from Table1
except
select distinct [column] from Table1;
Alternatively, you could use standard SQL
或者，您可以使用标准 SQL
select [column] from Table1
where [column} not in
(select distinct [column} from Table1);
回答by Nils
distinctwould be the keyword to filter douplicates. May be you can explain a little more what you're trying to achieve ?
distinct是过滤重复项的关键字。也许你可以解释一下你想要实现的目标？
