Write an SQL command that will find any customers who have not placed orders?

Question

Can anyone tell me which SQL command that will find any customers who have not placed orders?

Answer 1

Here is the SQL Query to find the customers details who have not placed orders:

SELECT Customer_Name

FROM Customers

WHERE Customer.id NOT IN

                                         (SELECT person_id

                                          FROM orders)

In the above query, the inner query returns the customer ids who placed orders. The outer query returns the customer names whose ids are not in the subquery using NOT IN operator.

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Answer 2

As per the question, lets take customer and orders as two tables.

Select * from customer join orders on customer.customerid=orders.customerid Where order.orderid is null

Here we are joining the orders and customer tables using join. Based on common column customerid. And checking for orderid in orders table is null.