Mysql Alter Table Syntax
Mysql Alter Table is used to redefine the existing table.
| ALTER TABLE tbl_name ADD [COLUMN] col_name column_definition |
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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