MySQL 如何修改MySQL视图的定义而不需要删除它？

借助ALTER VIEW语句，我们可以修改MySQL视图的定义。在这种情况下，我们无需将其删除。语法如下 –

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语法

ALTER VIEW view_name AS
SELECT column1,column2…
FROM table
WHERE conditions;

示例

为了说明这一点，我们正在修改名为’Info’的视图的定义，其中包含以下数据 –

mysql> Select * from Info;
+------+---------+------------+
| Id   | Name    | Subject    |
+------+---------+------------+
| 101  | YashPal | History    |
| 105  | Gaurav  | Literature |
| 125  | Raman   | Computers  |
| 130  | Ram     | Computers  |
+------+---------+------------+
4 rows in set (0.01 sec)

现在，假设我们想要在此视图中添加一列，则可以使用ALTER VIEW语句完成，如下所示 –

mysql> Alter view info AS SELECT ID, NAME, SUBJECT, ADDRESS from student_info;
Query OK, 0 rows affected (0.07 sec)

mysql> Select * from info;
+------+---------+------------+------------+
| ID   | NAME    | SUBJECT    | ADDRESS    |
+------+---------+------------+------------+
| 101  | YashPal | History    | Amritsar   |
| 105  | Gaurav  | Literature | Chandigarh |
| 125  | Raman   | Computers  | Shimla     |
| 130  | Ram     | Computers  | Jhansi     |
+------+---------+------------+------------+
4 rows in set (0.00 sec)