Question

I want to merge two rows and add a column to show the count of similar rows.

I don’t want to update the table, I just want this as part of select statement which would further be used in Java. I think it would be more efficient to do this in SQL then doing things after retrieving the records. It would be great if you could give me some idea how to do this in SQL:

Answer 1

Something like this?

select tb1.id, tb1.user, count(*)
from Table1 tb1
    left join Table2 tb2 on
        tb1.user = tb2.user
group by tb1.id, tb1.user
order by tb1.id

Output:

id          user       count 
----------- ---------- -----------
1           A          1
2           B          2
3           C          2
4           D          3
5           E          1