Dealing with time-keeping and changing entries

Question

Hi everyone, I'm working on a project for school, and I have to develop a database that works somewhat like eBay. Only instead of auctions users create and place bets.
My question is, how would I go about implementing some sort of function that will allow me to change the status of a table entry once its BetTime (or in the case of eBay, Bid Life) ends?
an example of this would be:
BetID BetCreationTime BetEndTime Status
000 12:00 BetCreationTime + 5 hours OPEN
001 3:00 BetCreationTime + 8 hours OPEN
5 hours after Bet 000 is created (5:00), it must change status to CLOSED. The same goes for bet 001 8 hours after it is created (at 11:00)

Answer 1

Have a play with this Example in SQL and PL/SQL. Note that I do not want to store my STATUS because I need to get it at runtime.
SQL> CREATE TABLE BET
2 (BetID NUMBER(10)
3 ,BetCreationTime DATE
4 ,BetEndTime DATE)
5 /
Table created.
SQL> INSERT INTO BET VALUES (100,sysdate,sysdate+5)
2 /
1 row created.
SQL> INSERT INTO BET VALUES (101,sysdate,sysdate+7)
2 /
1 row created.
SQL> INSERT INTO BET VALUES (102,sysdate,sysdate-1)
2 /
1 row created.
SQL> commit;
Commit complete.
SQL> SELECT BetID
2 ,TO_CHAR(BetCreationTime,'DD-MON-YYYY HH24:MI:SS') Starting
3 ,TO_CHAR(BetEndTime,'DD-MON-YYYY HH24:MI:SS') Ending
4 ,round(BetEndTime-SYSDATE) "Remaining(Days)"
5 FROM BET;
BETID STARTING ENDING Remaining(Days)
100 01-NOV-2005 18:33:32 06-NOV-2005 18:33:32 5
101 01-NOV-2005 18:33:32 08-NOV-2005 18:33:32 7
102 01-NOV-2005 18:33:33 31-OCT-2005 18:33:33 -1
SQL> SET VERIFY OFF
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 BET_REMAIN NUMBER(10);
3 BET_STATUS VARCHAR(10);
4 BET_ENDDATE VARCHAR(11);
5 BET_ENDTIME VARCHAR(10);
6 BEGIN
7 SELECT round(BetEndTime-SYSDATE)
8 ,TO_CHAR(BetEndTime,'DD-MON-YYYY')
9 ,TO_CHAR(BetEndTime,'HH24:MI:SS')
10 INTO BET_REMAIN,BET_ENDDATE,BET_ENDTIME
11 FROM BET
12 WHERE BETID=&BETID;
13
14 IF BET_REMAIN <= 0
15 THEN
16 BET_STATUS := 'CLOSED';
17 DBMS_OUTPUT.PUT_LINE('This Bet is Closed on '||BET_ENDDATE||' at '||BET_ENDTIME);
18 ELSE
19 BET_STATUS := 'OPEN';
20 DBMS_OUTPUT.PUT_LINE('This Bet is Open for another '||BET_REMAIN||' Days Untill '||BET_ENDDATE||' at '||BET_ENDTIME);
21 END IF;
22
23 EXCEPTION WHEN NO_DATA_FOUND
24 THEN
25 DBMS_OUTPUT.PUT_LINE('This Bet does not Exist');
26 END;
27 /
Enter value for betid: 100
This Bet is Open for another 5 Days Untill 06-NOV-2005 at 18:33:32
PL/SQL procedure successfully completed.
SQL> /
Enter value for betid: 101
This Bet is Open for another 7 Days Untill 08-NOV-2005 at 18:33:32
PL/SQL procedure successfully completed.
SQL> /
Enter value for betid: 102
This Bet is Closed on 31-OCT-2005 at 18:33:33
PL/SQL procedure successfully completed.
SQL> /
Enter value for betid: 103
This Bet does not Exist
PL/SQL procedure successfully completed.
SQL>