mysql left join funktioniert nicht code example

Example 1: mysql left join

/*Two tables: CUSTOMERS table and ORDERS table.
ORDERS table contains STATUS attribute.*/
SELECT 
    customers.customerNumber, 
    customerName, 
    orderNumber, 
    status
FROM
    customers
LEFT JOIN orders ON 
    orders.customerNumber = customers.customerNumber;

Example 2: left join mysql

SELECT 
    Student_details.*,
    Attendance.*
FROM
    Student_details
LEFT JOIN Attendance ON 
    Student_details.s_id = Attendance.s_id;