Mysql Alter Drop
Mysql Alter Drop is used to modify the table definition and delete the column from table.
Understand with Example
The Tutorial illustrate an example from 'Mysql Alter Drop'. To understand this example, we create a table 'employees' with required field name and datatype. The table employee have a Empid as Primary Key.
Query to create table:
CREATE TABLE `employees` (
->Empid int(10),
->Empname varchar(60),
->date date
->PRIMARY KEY(Empid)
->);
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Query to insert data into Table named employees:
The Query insert into adds the records or rows into table 'employees'.
mysql>insert into employees values(01,'Girish','2008-12-22','nainital','[email protected]'); Query OK, 1 row affected (0.02 sec) mysql>insert into employee1 values(02,'Komal','2008-12-23','Meerut','[email protected]'); Query OK, 1 row affected (0.02 sec)
Query to view data of Table named employees:
To view the detail from table 'employees' we use select query that return the detail of employees.
mysql> select * from employees; |
Output:-
+-------+---------+------------+----------+-------------+ | empid | empname | date | city | email | +-------+---------+------------+----------+-------------+ | 1 | Girish | 2008-12-22 | nainital | [email protected] | | 2 | Komal | 2008-12-23 | Meerut | [email protected] | +-------+---------+------------+----------+-------------+ 2 rows in set (0.00 sec) |
Query to drop column from Table named employees using alter command :
The alter Query modifies the definition of table employees and delete the fieldname 'email' from the table 'employees'.
mysql> alter table employees
-> drop column email;
Query OK, 2 rows affected (0.14 sec)
Records: 2 Duplicates: 0 Warnings: 0
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Output after dropping column:-
mysql> select * from employees; +-------+---------+------------+----------+ | empid | empname | date | city | +-------+---------+------------+----------+ | 1 | Girish | 2008-12-22 | nainital | | 2 | Komal | 2008-12-23 | Meerut | +-------+---------+------------+----------+ 2 rows in set (0.00 sec) |
