Resolve MySQL group by cannot sort method

The usual method

The code is as follows	Copy Code
SELECT * FROM table group BY column_name ORDER by id DESC

is not able to get the maximum value of the ID within each packet.

Workaround:

Someone writes the following statement:

The code is as follows	Copy Code
SELECT *,max (Dateline) as Max_line from posts GROUP by Tid order by Dateline DESC LIMIT 10

This statement is correct to select the maximum release time, but you can compare Dateline and max_dateline is not equal! (There may be quite

Situation, that is, the target record of the group is only one time! )

The correct approach is:

The code is as follows	Copy Code
SELECT *,max (Dateline) as Max_line from posts GROUP by Tid has Dateline=max (Dateline) Order BY Dateline DESC LIMIT 10 Or SELECT * FROM (SELECT * to table ORDER BY id desc) T GROUP BY column_name ORDER by id DESC

This will

The maximum ID value is obtained for each packet, and the last order by id DESC is then sorted by the values of the resulting IDs