Difference between SQL Intersect VS EXCEPT.

INTERSECT

• Returns only common rows from both queries
• Works like: A ∩ B
• Removes duplicates

EXCEPT

• Returns rows from first query minus second query
• Works like: A − B
• Removes duplicates

Example:

-- INTERSECT
SELECT Name FROM Students
INTERSECT
SELECT Name FROM Teachers;
-- → common names in both tables

-- EXCEPT
SELECT Name FROM Students
EXCEPT
SELECT Name FROM Teachers;
-- → names in Students but not in Teachers

Key idea:

• INTERSECT = common data
• EXCEPT = exclude second result from first