Mysql Alter Table
Mysql Alter Table is used to redefine the existing table.
Understand with Example
The Tutorial illustrate an example from 'Mysql Alter Table'. To grasp this
example we create a table 'employees'. The create table statement is used
to create a table 'employees' with different fieldname and datatype
respectively. The table have a Primary Key column 'empid'.
Query to create table:
CREATE TABLE employees (
->Empid int(10),
->Empname varchar(60),
->date date
->PRIMARY KEY(Empid)
->);
|
Query to insert data into Table named employees:
The Query insert into add the records or rows into table 'employees'.
mysql>insert into employees values(01,'Girish','2008-12-22');
Query OK, 1 row affected (0.02 sec)
mysql>insert into employee1 values(02,'Komal','2008-12-23');
Query OK, 1 row affected (0.02 sec)
|
Query to view data of Table named employees:
To view the detail of table 'employees' we use select query
that returns the detail of table 'employees'.
mysql> select * from employees;
|
Output:-
+-------+---------+------------+
| Empid | Empname | date |
+-------+---------+------------+
| 1 | Girish | 2008-12-22 |
| 2 | Komal | 2008-12-23 |
+-------+---------+------------+
2 rows in set (0.00 sec)
|
Query to alter Table named employees by adding column named city:
The Query Alter is used to modify the table 'employees' and add
keywords is used to add the column name 'city' to the existing table.
mysql> alter table employees
-> add column city varchar(30);
Query OK, 2 rows affected (0.13 sec)
Records: 2 Duplicates: 0 Warnings: 0
|
Output:-
mysql> select * from employees;
+-------+---------+------------+------+
| Empid | Empname | date | city |
+-------+---------+------------+------+
| 1 | Girish | 2008-12-22 | NULL |
| 2 | Komal | 2008-12-23 | NULL |
+-------+---------+------------+------+
2 rows in set (0.02 sec)
|
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