GROUP BY订购

Question

SELECT * FROM title gives me the following output:

title_number    version_type    hd_sd
1000046         Standard    SD
1000046         Standard    HD
1000050         Standard    SD
1000093         Standard    SD
1000093         Standard    HD
1000125         Standard    SD
1000269         Standard    SD

I need to get all distinct title_numbers and then hd_sd will = HD if that exists, otherwise, it will = SD . The correct output would be:

title_number    version_type    hd_sd
1000046         Standard    HD
1000050         Standard    SD
1000093         Standard    HD
1000125         Standard    SD
1000269         Standard    SD

The closest I got to this was SELECT * FROM title GROUP BY title_number , but that does not give me the correct hd_sd column value. How would I correctly do this query?

Answer 1

SELECT title_NUMBer, Version_type,
        MIN(hd_sd)
FROM tableName
GROUP BY title_NUMBer

for improvements,

SELECT a.*
FROM    tableName a
        INNER JOIN
        (
            SELECT title_NUMBer, MIN(hd_sd) minCol
            FROM tableName
            GROUP BY title_NUMBer
        ) b ON a.title_number = b.title_Number AND
                a.hd_sd = b.mincol