SELECT DISTINCT仍显示重复项 [英] SELECT DISTINCT still showing duplicates

问题描述

是的，关于SO的问题有上千个，但我已经搜索了半个小时，但尚未找到解决方案.

Yes, there's a thousand questions about this on SO, but I've been searching for half an hour and I've yet to find a solution.

所以，我有一个像这样的表:

So, I've a table like this:

这是我的查询:

SELECT DISTINCT rengasID,leveys FROM renkaat ORDER BY leveys ASC

这是我得到的结果:

如果您有这个主意，我会在其中填充一个选择字段，但是它仍然有重复项.

If you get the idea, I'm populating a select field with it, but it still has duplicates.

我在做什么错了?

推荐答案

如果要使用不同的levey，只需选择该字段即可:

If you want distinct leveys, just choose that field:

SELECT DISTINCT leveys
FROM renkaat
ORDER BY leveys ASC

rengasid在每一行上都有不同的值.

The rengasid has a different value on each row.

distinct子句适用于所有返回的列，无论括号如何.

The distinct clause applies to all the columns being returned, regardless of parentheses.

如果结果中需要regasid，请使用group by:

If you need the regasid in the result, then use group by:

select leveys, min(regasid) as regasid
from renkaat
group by leveys
order by leveys asc;

这给出了第一个ID.如果需要所有它们，可以使用group_concat()将它们放在列表中.如果每行都需要一个单独的ID，那么您就有重复项了.

This gives the first id. If you need all of them, you can get them in a list using group_concat(). If you need a separate id on each row, well, then you have duplicates.

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