MySQL Group_Concat按ID区分

Question

Is it possible to group_concat records by distinct Ids:

GROUP_CONCAT(Column2 BY DISTINCT Column1)

I need to get the values from column2 by distinct values from column1 . Because there are repeating values in column 2, that's why I can't use distinct on column2 .

Any thoughts on this? Thanks!

EDIT 1

Sample Table Records:

ID  Value
1   A
1   A
2   B
3   B
4   C
4   C

Using the GROUP_CONCAT the I wanted [ GROUP_CONCAT(Value BY DISTINCT Id) ], I will have an output:

A, B, B, C

EDIT 2

Somehow got my group_concat working:

GROUP_CONCAT(DISTINCT CONCAT(Id, '|', Value))

This will display the concatenated values by distinct id, just need to get rid of the Id somewhere. You can do it without the concat function, but I need the separator. This may not be a good answer but I'll post it anyway.

Answer 1

Try this one, ( the simpliest way )

SELECT GROUP_CONCAT(VALUE)
FROM
(
    SELECT DISTINCT ID, VALUE
    FROM TableName
) a

SQLFiddle Demo

Answer 2

GROUP_CONCAT函数支持DISTINCT表达式。

SELECT id, GROUP_CONCAT(DISTINCT value) FROM table_name GROUP BY id

Answer 3

这应该工作：

SELECT GROUP_CONCAT(value) FROM (SELECT id, value FROM table GROUP BY id, value) AS d