Customers Without Purchase Activity

Easy

Your commerce analytics team maintains two relational tables: Customers: master customer records with id and name Orders: checkout events with order id and customerId Build a report that returns every customer who has never placed an order. Output requirements: Return exactly one column named Customers. Include customer names where Customers.id does not appear in Orders.customerId. Return rows in any order unless your local checker requires deterministic sorting. This problem must be solved for: SQL (SQLite 3.27.2) Pandas

Example 1

Input

Customers:
| id | name  |
|----|-------|
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |

Orders:
| id | customerId |
|----|------------|
| 1  | 3          |
| 2  | 1          |

Output

[
  {"Customers":"Henry"},
  {"Customers":"Max"}
]

Explanation

Customers 2 and 4 do not appear in Orders.customerId, so they are returned.

Example 2

Input

Customers:
| id | name  |
|----|-------|
| 10 | Ana   |
| 11 | Omar  |

Orders:
| id | customerId |
|----|------------|
| 90 | 10         |
| 91 | 10         |

Output

[
  {"Customers":"Omar"}
]

Explanation

Multiple orders from the same customer still mean that customer is active. Only customer 11 has no order.

Example 3

Input

Customers:
| id | name   |
|----|--------|
| 7  | Priya  |
| 8  | Arjun  |

Orders:
| id | customerId |
|----|------------|
| 1  | null       |
| 2  | 8          |

Output

[
  {"Customers":"Priya"}
]

Explanation

A null customerId in Orders does not match any customer. Only customer 8 has a valid order reference.

Constraints

1 <= number of rows in Customers <= 10,000
0 <= number of rows in Orders <= 10,000
Customers.id is unique
Orders.id is unique
Orders.customerId may include IDs not present in Customers (or null in imperfect data feeds)
Use SQLite 3.27.2 semantics for SQL submissions
For Pandas submissions, return a DataFrame with exactly one column: Customers