SQL logic help for pl/sql block

Question

Hi All,
I need your suggestions and comments for the below issue:
I have two tables: table A and table B
Table A has two columns as id and counts:
Id Counts
99 10
999 13
9999 7
Table B has two columns as Id and order:
Id Order
99 1
999 2
9999 3
We need to update Order in Table B such that Id having highest count in table A has Order as 1 in table B and it keep on increasing the order for other Ids based on decreasing counts in table A. This will be like a job which will run daily and look for counts in table A and update Order in table B according to it.
It seems to be simple but i am not getting it. Please help me out of this by writing some PL/SQL block.
I will really appreciate your all comments and responses.
Regards
Dev

Answer 1

Hi,
Keen2Learn wrote:
Hi All,
I am really greatful to all fo you for all your replies and comments. I change ORDER table to ORDERS. All you replies worked for me but there is some slight change in scenario which i need to discuss with you all.
E.g: Table A has 10 rows like below:
Id Counts Type
99 10 A
999 13 A
9999 7 C
99 4 B
999 2 C
88 2 A
77 1 C
777 3 B
777 5 A
888 2 CIf you'd like help, please post CREATE TABLE and INSERT statements for your sample data (including table b as it is before the UPDATE or MERGE).
I populate data in Orders column Table B based on id, by grouping sum of counts for that id in table A.
Id 999 has highest sum(count) as 15, so it has orders as 1 in Table B and do same for descending counts for each Id.
Table B has 5 rows like below:
Id Orders
99 2
999 1
88 4
777 3
555 5
Assume Table B as static(no new record comes in it) but only its Orders changes for each Id based on counts for that Id in Table A. As you see, Table B has id 555 which is not in Table A, so we need to update its orders to the highest number by taking its Count as 0(zero). Sorry, it's unclear what you want to do.
Post what you'd like table b to look like after the UPDATE or MERGE.
Right now i am doing it like this:
declare
     cursor c1 is
     select Id, SUM (COUNT), RANK () OVER (ORDER BY SUM (COUNT)) rnk
     from TableA      AND Id IN (SELECT Id FROM TableB)
GROUP BY Id
ORDER BY rnk DESC;
i NUMBER := 1;
begin
for curr in c1
loop
     update TableB      
set orders = i
     where id = curr.id;
     i := i + 1;
end loop;
end;I'm not sure what you're trying to do, but I'll bet you don't need PL/SQL to do it. Use a single UPDATE or MERGE statement (inside PL/SQL if necessary).
But it is not updating orders for Id 555 in TableB.There is no row for id=555 in table b, and, according to your requirements, there never will be, because "Table B as static(no new record comes in it)". It's behaving exactly as you said you wanted it to. What's the problem?
Please provide your suggesstions on what needs to be done to take care of this scenario. I will really appreciate your all suggesstions and comments. Please let me know if need some more explanation.Whenever you have a problem, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only), and the results you want from that data.
In the case of a DML operation (such as UPDATE) the sample data should show what the tables are like before the DML, and the results will be the contents of the changed table(s) after the DML.
Explain, using specific examples, how you get those results from that data.
Always say what version of Oracle you're using.