我想在MySQL数据库中取出重复的记录。这可以用:

SELECT address, count(id) as cnt FROM list
GROUP BY address HAVING cnt > 1

结果是:

100 MAIN ST    2

我想要拖动它,以便它显示复制的每一行。喜欢的东西:

JIM    JONES    100 MAIN ST
JOHN   SMITH    100 MAIN ST

有什么想法可以做到吗?我试图避免做第一个,然后在代码中用第二个查询查找重复。


当前回答

会是这样的:

SELECT  t1.firstname t1.lastname t1.address FROM list  t1
    INNER JOIN  list t2 
    WHERE 
        t1.id < t2.id AND 
        t1.address = t2.address;

其他回答

不是很有效,但应该可以工作:

SELECT *
FROM list AS outer
WHERE (SELECT COUNT(*)
        FROM list AS inner
        WHERE inner.address = outer.address) > 1;

关键是重写这个查询,以便它可以用作子查询。

SELECT firstname, 
   lastname, 
   list.address 
FROM list
   INNER JOIN (SELECT address
               FROM   list
               GROUP  BY address
               HAVING COUNT(id) > 1) dup
           ON list.address = dup.address;

这样不是更简单吗?

SELECT *
FROM tc_tariff_groups
GROUP BY group_id
HAVING COUNT(group_id) >1

?

会是这样的:

SELECT  t1.firstname t1.lastname t1.address FROM list  t1
    INNER JOIN  list t2 
    WHERE 
        t1.id < t2.id AND 
        t1.address = t2.address;

Powerlord的答案确实是最好的,我建议再做一个改变:使用LIMIT来确保db不会超载:

SELECT firstname, lastname, list.address FROM list
INNER JOIN (SELECT address FROM list
GROUP BY address HAVING count(id) > 1) dup ON list.address = dup.address
LIMIT 10

如果没有WHERE和when连接,使用LIMIT是一个好习惯。从小值开始,检查查询有多重,然后增加限制。