LEFT JOIN is to return all the rows in table 1 and match the rows in the table 2 when there are matches. So your code is not working.
Whatever after ON, should has "equal" sign included, not something like "<>". You will need add extra lines if you want to use LEFT JOIN
# Write your MySQL query statement below SELECT c1.Name as Customers FROM ( SELECT c.Name, o.Id FROM Customers c LEFT JOIN Orders o ON c.Id = o.CustomerId ) c1 WHERE c1.Id is NULL;