Get Data Of Third Column Based on Two other Columns - sql

Question

This is a sample table
ID STOREA STOREB STOREC AB BC CA ABC
--- ------- ------ ------- -- -- --- ---
10 1 0 0
10 0 1 0
10 0 1 0
29 0 1 0
29 0 0 1
29 1 0 0
Each row corresponds to a purchase made at either of Store A or B or C. Customer 10 shops at A and B but not c. So I want AB=1 BC=0 CA=0 ABC=0 for all ID=10 rows and for ID=29, he shops at all 3, so I need AB=1 BC=1 CA=1 ABC=1 for all rows where ID=29 (using ORACLE SQL)
I would like to update the columns in the table.

Answer 1

Here is one way you can do this. I don't think you can use JOINs in Oracle with UPDATE statements -- however, you can accomplish the same thing by using MERGE:
MERGE
INTO yourtable
USING (
select id as idnew,
case when a + b = 2 then 1 else 0 end abnew,
case when b + c = 2 then 1 else 0 end bcnew,
case when a + c = 2 then 1 else 0 end acnew,
case when a + b + c = 3 then 1 else 0 end abcnew
from (
select
id,
max(case storea when 1 then 1 else 0 end) A,
max(case storeb when 1 then 1 else 0 end) B,
max(case storec when 1 then 1 else 0 end) C
from yourtable
group by id
) a
)
ON (id = idnew)
WHEN MATCHED THEN
UPDATE
SET ab = abnew,
bc = bcnew,
ac = acnew,
abc = abcnew
SQL Fiddle Demo

Answer 2

Here is how you can do this as a select:
update (select id, storea, storeb, storec, AB as new_AB, BC as new_BC, AC as new_AC, ABC as new_ABC
from t join
(select id,
(case when max(storeA) = 1 and max(storeB) = 1 then 1 else 0 end) as AB,
(case when max(storeB) = 1 and max(storeC) = 1 then 1 else 0 end) as BC,
(case when max(storeA) = 1 and max(storeC) = 1 then 1 else 0 end) as AC,
(case when max(storeA) = 1 and max(storeB) = 1 and max(storeC) = 1 then 1 else 0 end) as ABC
from t
group by id
) tsum
on t.id = tsum.id
)
set AB = new_AB, AC = new_AC, BC = new_BC, ABC = new_ABC;
I think this might work:
select id, storea, storeb, storec, AB, BC, AC, ABC
from t join
(select id,
(case when max(storeA) = 1 and max(storeB) = 1 then 1 else 0 end) as AB,
(case when max(storeB) = 1 and max(storeC) = 1 then 1 else 0 end) as BC,
(case when max(storeA) = 1 and max(storeC) = 1 then 1 else 0 end) as AC,
(case when max(storeA) = 1 and max(storeB) = 1 and max(storeC) = 1 then 1 else 0 end) as ABC
from t
group by id
) tsum
on t.id = tsum.id
)
set AB = new_AB, AC = new_AC, BC = new_BC, ABC = new_ABC;