MySQL 如何使用LEFT JOIN创建MySQL视图?
为了演示使用“Customers”和“Reserve”表中的下列数据制作MySQL视图,我们使用以下数据 –
mysql> Select * from customers;
+-------------+----------+
| Customer_Id | Name |
+-------------+----------+
| 1 | Rahul |
| 2 | Yashpal |
| 3 | Gaurav |
| 4 | Virender |
+-------------+----------+
4 行数据(0.00 秒)
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 行数据(0.00 秒)
通过在上述表上使用LEFT JOIN,以下查询将创建名为“customer_VLeft”的视图;该视图将有未对任何汽车进行预订的客户名称。
mysql> Create view customer_Vleft AS SELECT NAME from customers LEFT JOIN RESERVE ON customer_id = id WHERE id IS NULL;
查询 OK,0 行受影响(0.13 秒)
mysql> Select * from customer_Vleft;
+----------+
| NAME |
+----------+
| Virender |
+----------+
1 行数据(0.00 秒)
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