如何使用sql查询基于客户名删除唯一行？

Question

我有一张表如下：

cust_name   cust_address  sex  orderactive
xxxx        yyy            m    1
iiii        iii            f    1
xxxx        yyy            m    1

我想保留重复的条目和删除唯一的条目，我的结果表（删除重复项后）应该看起来像 -

cust_name   cust_address  sex  orderactive
xxxx        yyy            m    1
xxxx        yyy            m    1

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Answer 1

您可以使用以下查询：

SELECT cust_name
FROM mytable
GROUP BY cust_name
HAVING COUNT(*) > 1

获取重复记录的cust_name值。

将此查询用作派生表并连接回原始表以获得所需结果：

SELECT t1.*
FROM mytable AS t1
JOIN (
   SELECT cust_name
   FROM mytable
   GROUP BY cust_name
   HAVING COUNT(*) > 1
) AS t2 ON t1.cust_name = t2.cust_name

Answer 2

您可以通过以下方式使用群组：

SELECT *
FROM Persons
WHERE cust_name IN
    (SELECT cust_name
     FROM Persons
     GROUP BY cust_name
     HAVING count(cust_name) > 1)

http://sqlfiddle.com

Answer 3

您可以使用以下查询从表中删除唯一行。唯一行标识为HAVING COUNT(cust_name) = 1。

DELETE FROM cust_details 
WHERE cust_name 
IN (
    SELECT cust_name 
    FROM (SELECT * FROM cust_details) AS cust_details_alias 
    GROUP BY cust_name HAVING COUNT(cust_name) = 1
    );

Answer 4

使用子查询获取重复行的id，然后将在where条件中使用。您的解决方案是：

select DISTINCT * from tbl as tbl1 
where cust_name IN (
Select cust_name from tbl where 1 < (
Select count(*) from tbl where cust_name = tbl1.cust_name))