Need the logic to retrieve the data from the table

Question

Hi ,
I have a table with the following data
ID Dept Sal
100 a 10
100 b 20
100 c 30
100 d 40
200 b 20
200 c 30
200 d 40
300 c 30
300 d 40
400 d 40
I want to retrieve the ID's from the above table based on the below logic..
a) If an ID is in Dept 'a' do not retrieve that ID.
b) If an ID does not exist in Dept 'a' then check if its in Dept 'B' and retrive only that row.
200 b 20
c) If an ID does not exist in Dept 'a' then check if its in Dept 'B' if not avaiable then
check for DEPT 'c' and 'd' and retrieve the Dept 'c' but Sal is calculated as sal of C*D
Result: 300 c 120 ( instead of 300 c 30 )
d) If an ID does not exist in Dept 'a' then check if its in Dept 'B' if not avaiable then
check for DEPT 'c' and 'd' , if not avaiable then and retrieve the Dept 'd'
Result: 400 d 40
Following should be the final result..
ID Dept Sal
200 b 20
300 c 30
300 d 120
400 d 40
I have around 25 million records in that table and the query should be included in the form of view or it shd be included in a view,so that it should not effect previous and present data.
Thanks in advance..
soumy

Answer 1

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