Join for first

Question

Hello Everybody!
I have run into a common situation but I can't find the perfect solution.
I have two tables: transaction and event with one to many connection. One transaction may have one or more events. I need a join-query to get transaction and not all events related to this transaction but only the oldest one.
ex.
Transaction table --------------- Event table
TransactionID ......-------------- EventID....Timestamp
1------------------------------------------10-----------1980 =>OK
2------------------------------------------11-----------1981 => It's OK this is older than 12
2------------------------------------------12-----------1982 => I don't need this!
3------------------------------------------13-----------1980 =>OK
Thanks Your Help!
Topicfun

Answer 1

Hello Everybody!
I have run into a common situation but I can't find
the perfect solution.
I have two tables: transaction and event with one to
many connection. One transaction may have one or more
events. I need a join-query to get transaction and
not all events related to this transaction but only
the oldest one.
ex.
Transaction table --------------- Event table
TransactionID ......--------------
EventID....Timestamp
1------------------------------------------10---------
--1980 =>OK
2------------------------------------------11---------
--1981 => It's OK this is older than 12
2------------------------------------------12---------
--1982 => I don't need this!
3------------------------------------------13---------
--1980 =>OK
Thanks Your Help!
Topicfuncreate table my_transaction (transaction_id number(10));
insert into my_transaction values(1);
insert into my_transaction values(2);
insert into my_transaction values(2);
insert into my_transaction values(3);
create table my_event (transaction_id number(10),event_id number(10),my_dt timestamp(6));
insert into my_event values (1,10,sysdate);
insert into my_event values (2,11,sysdate);
insert into my_event values (2,12,sysdate);
insert into my_event values (3,13,sysdate);
select E.transaction_id,min(E.event_id),to_char(E.my_dt,'yyyy') from my_event E,my_transaction T
where T.TRANSACTION_ID=E.transaction_id
group by E.transaction_id,to_char(E.my_dt,'yyyy')
order by E.TRANSACTION_ID