Add column in table of Oracle, Sql Server, Mysql & Postgresql

Sometime after creating the database schema and sturture we have to modified or add column in the table for future updates. So we need to modified the structure of the tables for future deployment. We can use this command to add column in databases.

Following are the example of add column in the table

Syntax:

ALTER TABLE

Example
Suppose need to add one more column in employee table
alter table employee add dateofjoin datetime;

SQL Server

ALTER TABLE table_name ALTER COLUMN column_name datatype;
ALTER TABLE dbo.table_name DROP COLUMN column_name;


Oracle

Alter table table_name modify column_name datatype;
alter table table_name drop column col_name1;


MySQL

ALTER TABLE MODIFY COLUMN datatype;
ALTER TABLE DROP ;


PostgreSQL

ALTER TABLE ADD COLUMN datatype ;
ALTER TABLE DROP COLUMN RESTRICT;