Good wrap-up on ON vs WHERE

You chose ON correctly for preserving left rows; that keeps unmatched left rows with NULLs while WHERE would filter them out afterward. Remember that where you place conditions changes whether aggregation later sees those NULLs.

From JOIN placement to aggregation

Bridge: Now shift from JOIN placement to aggregation — joins affect which rows get aggregated. Match each aggregation need to the best technique to use with joins.

Match each requirement (left) with the best approach (right).Get total order amount per customer, but still include customers who have no orders.Return only customers who have at least one order and show their order counts.Filter aggregated groups to those with total > 1000.Compute a running total of orders per customer ordered by order_date.

How was this question?

Too easyAbout rightToo hard

Learning: MYSQL