Customers Who Never Order, customersorder

Customers Who Never Order, customersorder

Suppose that a website contains two tables, the MERs table and the Orders table. write a SQL query to find all customers who never order anything. table: MERs. + ---- + ------- + | Id | Name | + ---- + ------- + | 1 | Joe | 2 | Henry | 3 | Sam | 4 | Max | + ---- + ------- + table: orders. + ---- + ------------ + | Id | CustomerId | + ---- + ------------ + | 1 | 3 | 2 | 1 | + ---- + ------------ + Using the above tables as example, return the following: + ----------- + | MERs | + ----------- + | Henry | Max | + ----------- + execute the left Outer Join and then judge the select name record of customerid is null, customerid from Customers c left outer join Orders o on c. id = o. customerid + ------- + ------------ + | name | customerid | + ------- + ------------ + | Joe | 1 | Henry | NULL | Sam | 3 | Max | NULL | + ------- + ------------ + select name as Customers from (select name, customerid from Customers c left outer join Orders o on c. id = o. customerid) t where t. customerid is null;