Dealing with NULL values and EMPTY strings in UNION of two tables I want return records from two database tables when a record differs in at least one of the fields.

I have written a query for it using the UNION operator.  It is working absolutely fine.

However, I want to treat NULL and '' (empty string) as the same value.

For example, all entries have a field Email-ID having value NULL in one table and '' in the other table.

Using the query I have, it is showing these two are different.  I want these two values to be treated the same.  I have around 15 such fields.

How do I do this?
Use ISNULL or COALESCE

SELECT COALESCE(A.NULLABLEFIELD,'') FROM A
UNION
SELECT COALESCE(B.NULLABLEFIELD,'') FROM B