sql - Combine multiple rows with different dates / variables to one row

Question

I have the following data represented in a table like this:

User	Type	Date
A	Mobile	2019-01-10
A	Mobile	2019-01-20
A	Desktop	2019-03-01
A	Desktop	2019-03-20

Answer 1

Hmmm . . . You can use row_number() (twice) and aggregation:

select user,
       max(case when seqnum_u = 1 then type end) as type1,
       max(case when seqnum_u = 1 then date end) as date1,
       max(case when seqnum_u = 2 then type end) as type2,
       max(case when seqnum_u = 2 then date end) as date2
from (select t.*,
             row_number() over (partition by user order by date) as seqnum_u
      from (select t.*,
                   row_number() over (partition by user, type order by date) as seqnum
            from t
           ) t
      where seqnum = 1
    ) t
group by user;