ALTER TABLE Syntax

ALTER TABLE

ADD datatype

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 ;

ALTER TABLE DROP COLUMN RESTRICT;