Question

I have 2 tables (say A and B) in a MS SQL DB representing customer transactions. Both share a column (say Column X).

Ideally information in table B is a subset of information in table A.

Can I run a SQL query to check based on Column X if all the values in Table B are present in Table A?

Thanks

Answer 1

select X
from A
LEFT OUTER JOIN B on A.x = B.X
WHERE B.X IS NULL

to get all records from table A that are not in table B. Or

select X
from B
LEFT OUTER JOIN A on A.x = B.X
WHERE A.X IS NULL

to get all records from table B that are not in table A.