Intermediate
Database Management Systems
Q65 / 100
What is the difference between UNION and UNION ALL?
Correct! Well done.
Incorrect.
The correct answer is B) UNION removes duplicates from combined results; UNION ALL keeps all rows including duplicates and is faster
B
Correct Answer
UNION removes duplicates from combined results; UNION ALL keeps all rows including duplicates and is faster
Explanation
UNION performs a DISTINCT sort to remove duplicates (slower). UNION ALL appends all rows from both queries without duplicate removal (faster). Use UNION ALL when duplicates are acceptable or not possible.
Progress
65/100