Flag based on combination of variables - sql

Question

I have a table A which looks like below-
Column1 Column2
0001M 80050
0001M 80053
0001M 80076
0001T 0002T
0001T 34800
0001T 34802
0001T 34804
0001T 36000
0001U 80500
0001U 80502
0001U 81105
0001U 81106
CREATE TABLE mytable(
Column1 VARCHAR(5) NOT NULL PRIMARY KEY
,Column2 VARCHAR(5) NOT NULL
);
INSERT INTO mytable(Column1,Column2) VALUES ('0001M','80050');
INSERT INTO mytable(Column1,Column2) VALUES ('0001M','80053');
INSERT INTO mytable(Column1,Column2) VALUES ('0001M','80076');
INSERT INTO mytable(Column1,Column2) VALUES ('0001T','0002T');
INSERT INTO mytable(Column1,Column2) VALUES ('0001T','34800');
INSERT INTO mytable(Column1,Column2) VALUES ('0001T','34802');
INSERT INTO mytable(Column1,Column2) VALUES ('0001T','34804');
INSERT INTO mytable(Column1,Column2) VALUES ('0001T','36000');
INSERT INTO mytable(Column1,Column2) VALUES ('0001U','80500');
INSERT INTO mytable(Column1,Column2) VALUES ('0001U','80502');
INSERT INTO mytable(Column1,Column2) VALUES ('0001U','81105');
INSERT INTO mytable(Column1,Column2) VALUES ('0001U','81106');
I have another table B which has the following columns -
ID SubID
1 0001M
1 80050
1 80053
1 12500
2 0001T
2 0002T
2 34800
2 36000
2 12506
3 80500
3 80502
3 81106
CREATE TABLE mytable(
ID INTEGER NOT NULL PRIMARY KEY
,SubID VARCHAR(5) NOT NULL
);
INSERT INTO mytable(ID,SubID) VALUES (1,'0001M');
INSERT INTO mytable(ID,SubID) VALUES (1,'80050');
INSERT INTO mytable(ID,SubID) VALUES (1,'80053');
INSERT INTO mytable(ID,SubID) VALUES (1,'12500');
INSERT INTO mytable(ID,SubID) VALUES (2,'0001T');
INSERT INTO mytable(ID,SubID) VALUES (2,'0002T');
INSERT INTO mytable(ID,SubID) VALUES (2,'34800');
INSERT INTO mytable(ID,SubID) VALUES (2,'36000');
INSERT INTO mytable(ID,SubID) VALUES (2,'12506');
INSERT INTO mytable(ID,SubID) VALUES (3,'80500');
INSERT INTO mytable(ID,SubID) VALUES (3,'80502');
INSERT INTO mytable(ID,SubID) VALUES (3,'81106');
Both the values of column1 and column2 of tableA should not occur together in SubID column within each distinct ID column of tableB. If it happens, I need to flag it 1. Otherwise 0. For example, (0001M, 80050) and (0001M, 80053) are not allowed to occur together. Since these two combinations exist in ID=1 of table B, it should be flagged 1.
The output should like this -
ID Flag
1 1
2 1
3 0
Reason Flag = 0 for ID=3 --> Since (80500, 80502) and (80502, 81106) come from column2 only (not from both column 1 and 2), they are allowed to occur together, it is flagged 0. I am using SQL Server 2016 version.

Answer 1

select
b1.ID,
max(case
when exists (select 1 from tableA a where a.Column1=b1.SubId and a.Column2=b2.SubId)
then 1 else 0 end) as flag
from
tableB b1
inner join table B b2 on b1.ID=b2.ID
group by b1.ID

Answer 2

you can also use JOINS to get this done like below.
Logic is that if we get id in tableA from tableB for each column and they are same then flag should be 1
see live demo
select
distinct B.id, flag =case when b1.id = b2.id then 1 else NULL end
from
mytableA A
left join mytableB b1 on b1.subid=a.column1
left join mytableB b2 on b2.subid=a.column2
right join
mytableB B
on B.id= case when b1.id = b2.id then b1.id else NULL end

Answer 3

Hmmm . . . This is tricky. I think this does what you want.
select b.id,
(case when count(*) > 0 then 1 else 0 end) as flag
from (select distinct b.id from b) b cross join
a join
b b1
on b1.subid = a.column1 and b1.id = b.id join
b b2
on b2.subid = a2.column2 and b2.id = b.id
group by b.id;