How to return rows from left table not found in right table?

Question

I have two tables with similar column names and I need to return records from the left table which are not found in the right table? I have a primary key(column) which will

Answer 1

I also like to use NOT EXISTS. When it comes to performance if index correctly it should perform the same as a LEFT JOIN or better. Plus its easier to read.

SELECT Column1
FROM TableA a
WHERE NOT EXISTS ( SELECT Column1
                   FROM Tableb b
                   WHERE a.Column1 = b.Column1
                 )