Count Visits with No Transactions for Each Customer

### Problem Find each customer with at least one Visits row having no matching transaction, and report customer_id and count_no_trans, the number of such visits. A customer may also have other visits with transactions. Any result row order is allowed. ### Tables Table: `Visits` ```text +-------------+---------+ | Column Name | Type | +-------------+---------+ | visit_id | int | | customer_id | int | +-------------+---------+ visit_id is the column with unique values for this table. This table contains information about the customers who visited the mall. ``` Table: `Transactions` ```text +----------------+---------+ | Column Name | Type | +----------------+---------+ | transaction_id | int | | visit_id | int | | amount | int | +----------------+---------+ transaction_id is column with unique values for this table. This table contains information about the transactions made during the visit_id. ``` ### Example ```text Visits (visit_id,customer_id): (1,8), (2,8), (3,8), (4,9), (5,10) Transactions (transaction_id,visit_id,amount): (1,1,20), (2,1,30), (3,4,40) Output (customer_id,count_no_trans): (8,2), (10,1) ``` ### What a Strong Answer Covers - Count visits without any transaction, even if the customer has transactions on other visits. - Return only qualifying customers and preserve the requested columns. ### Follow-up Questions - How would the result change if only successful transactions counted? - How would you return zero for customers who transacted on every visit?