Question

A data engineer has a large 'transactions' fact table and a smaller 'active_customers' table. They need to return only the transaction rows whose customer_id exists in active_customers, WITHOUT adding any columns from active_customers or duplicating transaction rows when a customer appears multiple times in the lookup. Which join type best accomplishes this?

Accepted Answer

LEFT SEMI JOIN between transactions and active_customers on customer_id

Answer

INNER JOIN between transactions and active_customers on customer_id

Answer

LEFT ANTI JOIN between transactions and active_customers on customer_id

Answer

LEFT OUTER JOIN between transactions and active_customers on customer_id