Tạo view dùng LEFT JOIN. Bảng Customers và Reserve:
mysql> Select * from customers;
+-------------+----------+
| Customer_Id | Name |
+-------------+----------+
| 1 | Rahul |
| 2 | Yashpal |
| 3 | Gaurav |
| 4 | Virender |
+-------------+----------+
4 rows in set (0.00 sec)
mysql> Select * from reserve;
+------+------------+
| ID | Day |
+------+------------+
| 1 | 2017-12-30 |
| 2 | 2017-12-28 |
| 2 | 2017-12-25 |
| 1 | 2017-12-24 |
| 3 | 2017-12-26 |
+------+------------+
5 rows in set (0.00 sec)
Tạo view customer_VLeft lấy khách chưa đặt chỗ (LEFT JOIN, lọc id IS NULL):
mysql> Create view customer_Vleft AS SELECT NAME from customers LEFT JOIN RESERVE ON customer_id = id WHERE id IS NULL;
Query OK, 0 rows affected (0.13 sec)
mysql> Select * from customer_Vleft;
+----------+
| NAME |
+----------+
| Virender |
+----------+
1 row in set (0.00 sec)