sql获取具有最大日期和相对id记录的行

Question

I try to make a simple query, spent on it a tone of hours and get nothing....
All I need is to get MAX date and all is corresponding fields.

I'm explain: I have a table with this fields: BasketID , OrderStatusTypeID , StatusDate .
I try to get only one record that contain OrderStatusTypeID value with the last StatusDate .

This is the data

BasketID    OrderStatusTypeID   date
1111        13              2013-04-01 11:38:31
1111        26              2013-04-04 17:44:17
1111        39              2013-04-02 12:35:07
1111        40              2013-04-08 12:52:55

This is my query:

SELECT BasketID, OrderStatusTypeID, max(StatusDate) date
FROM st
where BasketID=1111
group by BasketID

This is the results i need

BasketID    OrderStatusTypeID   date
63558       40          2013-04-08 12:52:55

For some reason I only get OrderStatusTypeID = 13 and not 40 ! (max of StatusDate, and NOT max of OrderStatusTypeID).
Why???

BasketID    OrderStatusTypeID   date
63558       13                   2013-04-08 12:52:55

Thanks for fast response!

Answer 1

I assume you are using MySQL because you can run the query even if you have not specified all the non-aggregate column in the GROUP BY clause.

There are many ways to solve the problem but I'm used to do it this way. The query uses a subquery which separately gets the latest date for every BasketID . Since the subquery returned only two columns, you need to join it back on the table itself to get the other columns provided that it match on two columns: BasketID , Date .

SELECT  a.*
FROM    st a
        INNER JOIN
        (
            SELECT  BasketID, MAX(Date) max_date
            FROM    st
            GROUP   BY BasketID
        ) b ON  a.BasketID = b.BasketID AND
                a.Date = b.max_date

Your query has executed successfully without throwing an exception even though there are non-aggregate columns that are not specified in the GROUP BY clause because it is permitted in MySQL. See MySQL Extensions to GROUP BY .

Answer 2

I know this is an old thread, but why isn't it possible to use ORDER BY and LIMIT in this case? A query like that:

SELECT * FROM st WHERE BasketID=1111 ORDER BY Date DESC LIMIT 1

Answer 3

Its pretty easy to use TOP command like:

SELECT TOP 1 * FROM st 
WHERE BasketID = 1111
ORDER BY date DESC