SQL alter view modification usage

Alter table allows you to modify the structure of an existing TABLE. For example, you can add or delete columns, create or delete indexes, change existing column types, or rename columns or tables. You can also change the comment and type of the table. You can also modify the view. See the following example. Alter view syntax ALTER [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}] VIEW view_name [(column_list)] AS select_statement [WITH [CASCADED | LOCAL] check option] This statement is used to change the definition of an existing view. Its syntax is similar to the create view mysql tutorial> 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> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (1, 'jason ', 'martin', '000000', '000000', 19960725, 'toronto ', 'programmer'); Query OK, 1 row affected (20060725 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (2, 'alison ', 'mathews ', '123', '123', 19760321, 'vancouver ', 'tester'); Query OK, 1 row affected (19860221 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (3, 'James ', 'Smith', '123', '123', 19781212, 'vancouver ', 'tester'); Query OK, 1 row affected (0.00 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, city, Description)-> values (4, 'celia ', 'Rice', '000000', '000000', 19821024, 'vancouver ', 'manager'); Query OK, 1 row affected (0.00 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (5, 'Robert ', 'black', '000000', '000000', 19840115, 'vancouver', 'tester'); Query OK, 1 row affected (19980808 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (6, 'linda ', 'green ', '20140901', '20160901', 19870730, 'New York ', 'tester'); Query OK, 1 row affected (19960104 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, City, Description)-> values (7, 'David ', 'Larry', '123', '123', 19901231, 'New York ', 'manager'); Query OK, 1 row affected (0.00 sec) mysql> insert into Employee (id, first_name, last_name, start_date, end_Date, salary, city, Description)-> values (8, 'James ', 'cat', '000000', '000000', 19960917, 'vancouver', 'tester'); Query OK, 1 row affected (0.00 sec) mysql> select * from Employee; + ------ + ------------ + ----------- + ------------ + --------- + ----------- + hour + | id | first_name | last_name | start_date | end_date | salary | city | description | + ------ + ------------ + hour ----------- + ------------ + --------- + ----------- + ------------- + | 1 | Jason | Martin | 1234.56 | 6661.78 | Toronto | Programmer | 2 | Alison | Mathews | | Vancouver | Tester | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | 4 | Celia | Rice | 1982-10-24 | 2344.78 | Vancouver | Manager | 5 | Robert | Black | 2334.78 | Vancouver | Tester | 6 | Linda | Green | 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 | 1232.78 | Vancouver | Tester | + ------ + ------------ + ----------- + ------------ + --------- + ----------- + ------------- + 8 rows in set (0.00 sec) 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> 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> 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> 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> drop view myView; Query OK, 0 rows affected (0.00 sec) mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql>