MySQL：如何从表中选择不同的值？

Question

I have huge table with many rows and columns, but I will describe only important of them:

+-----------+------------------+------+-----+---------+----------------+
| Field     | Type             | Null | Key | Default | Extra          |
+-----------+------------------+------+-----+---------+----------------+
| id        | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| name      | varchar(255)     | NO   |     | NULL    |                |
| artikel   | int(10) unsigned | NO   | IDX | NULL    |                |
| color     | varchar(255)     | NO   |     | NULL    |                |
+-----------+------------------+------+-----+---------+----------------+

Example data:

 1    apple        1000      red
 2    apple        1000      yellow
 3    lemon        2000      blue
 4    lem on       2000      green
 5    lemon        2000      black
 6    apple        1000      white
 7    cherry       3000      lime
 8    cherry       3000      pink
 9    lemon        2000      silver
10    apple        1000      gold

As you can see, the index is on artikel , each artikel has some name (for each artikel there is the same name ) and different color . Everything is OK, but with row 4 there is problem, there is wrong name = lem on , it should be lemon .

I want to select these rows ( GROUP BY artikel ), where there is not unique name , but HAVING COUNT(name) > 1 . So my select will return one row, where will be artikel = 2000 .

I tried HAVING , DISTINCT , but with no success.

How can be done that?

Answer 1

Use group by and having :

select artikel
from exampledata
group by artikel
having min(name) <> max(name);

You can also use count(distinct) in the having clause. But count(distinct) typically requires more work than just comparing the minimum and maximum values.