Question

I have a table like

 ___________
| id | date |
 -----------

with values like

1, 2012-02-21 04:04:04
2, 2012-02-21 05:03:05
3, 2012-02-22 03:03:03

Now, ask is to have a query which fetches 1 id/day which is corresponding to lower date
so, in this case query should return

id
---
1
3

// for date=2012-02-21, there are 2 rows, so row with id 1 is selected due to lower date value
// for date=2012-02-22, there is only 1 row, so corresponding id is picked

(Sorry for not a descriptive title)

Answer 1

You could try this:

SELECT
    SUBSTRING_INDEX(
        GROUP_CONCAT(
            `id`
            ORDER BY
                `date` ASC SEPARATOR ','
        ),
        ',',
        1
    ) AS `id`
FROM
    `table`
GROUP BY
    DATE(`date`)