ALTER TABLE允許你修改一個現有表的結構。例如，你可以增加或刪除列、創造或消去索引、改變現有列的類型、或重新命名列或表本身。你也能改變表的注釋和表的類型,當然也可以修改視圖了。下面看個實例。 ALTER VIEW語法 ALTER [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}] VIEW view_name [(column_list)] AS select_statement [WITH [CASCADED | LOCAL] CHECK OPTION] 該語句用於更改已有視圖的定義。其語法與CREATE VIEW類似 mysql教程> mysql> CREATE TABLE Employee( -> id int, -> first_name VARCHAR(15), -> last_name VARCHAR(15), -> start_date DATE, -> end_date DATE, -> salary FLOAT(8,2), -> city VARCHAR(10), -> description VARCHAR(15) -> ); Query OK, 0 rows affected (0.02 sec) mysql> mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values (1,'Jason', 'Martin', '19960725', '20060725', 1234.56, 'Toronto', 'Programmer'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(2,'Alison', 'Mathews', '19760321', '19860221', 6661.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(3,'James', 'Smith', '19781212', '19900315', 6544.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(4,'Celia', 'Rice', '19821024', '19990421', 2344.78, 'Vancouver','Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(5,'Robert', 'Black', '19840115', '19980808', 2334.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(6,'Linda', 'Green', '19870730', '19960104', 4322.78,'New York', 'Tester'); Query OK, 1 row affected (0.02 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(7,'David', 'Larry', '19901231', '19980212', 7897.78,'New York', 'Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description) -> values(8,'James', 'Cat', '19960917', '20020415', 1232.78,'Vancouver', 'Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id | first_name | last_name | start_date | end_date | salary | city | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ | 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer | | 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester | | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | | 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager | | 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester | | 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester | | 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager | | 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> mysql> Create VIEW myView (id,first_name,city) -> AS SELECT id, first_name, city FROM employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql> select * from myView; +------+------------+-----------+ | id | first_name | city | +------+------------+-----------+ | 1 | Jason | Toronto | | 2 | Alison | Vancouver | | 3 | James | Vancouver | | 4 | Celia | Vancouver | | 5 | Robert | Vancouver | | 6 | Linda | New York | | 7 | David | New York | | 8 | James | Vancouver | +------+------------+-----------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> ALTER VIEW myView (id,first_name,city) -> AS SELECT id, upper(first_name), city FROM employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql> select * from myView; +------+------------+-----------+ | id | first_name | city | +------+------------+-----------+ | 1 | JASON | Toronto | | 2 | ALISON | Vancouver | | 3 | JAMES | Vancouver | | 4 | CELIA | Vancouver | | 5 | ROBERT | Vancouver | | 6 | LINDA | New York | | 7 | DAVID | New York | | 8 | JAMES | Vancouver | +------+------------+-----------+ 8 rows in set (0.02 sec) mysql> mysql> drop view myView; Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> mysql> mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql>
