Question

I am sure my question is very simple for some, but I cannot figure it out and it is one of those things difficult to search an answer for. I hope you can help.

In a table in SQL I have the following (simplified data):

UserID   UserIDX   Number   Date
aaa      bbb       1        21.01.2000
aaa      bbb       5        21.01.2010
ppp      ggg       9        21.01.2009
ppp      ggg       3        15.02.2020
xxx      bbb       99       15.02.2020

And I need a view which will give me the same amount of records, but for every combination of UserID and UserIDX, there should be only 1 value under the Number field, i.e. the highest value found in the combination data set. The Date field needs to remain unchanged. So the above would be transformed to:

UserID   UserIDX   Number   Date
aaa      bbb       5        21.01.2000
aaa      bbb       5        21.01.2010
ppp      ggg       9        21.01.2009
ppp      ggg       9        15.02.2020
xxx      bbb       99       15.02.2020

So, for all instances of aaa+bbb combination the unique value in Number should be 5 and for ppp+ggg the unique number is 9.

Thank you very much.

Leo

Answer 1

select userid,useridx,maxnum,date
from table a
inner join (
    select userid,useridx,max(number) maxnum
    from table
    group by userid,useridx) b
 on a.userid = b.userid and a.useridx = b.useridx