Alter table in Oracle

Alter table to add column

CREATE Table Employee
(
Id int PRIMARY KEY ,
Name VARCHAR2(100)
);

ALTER TABLE Employee
ADD
(
Email VARCHAR2(50)
);

Alter table to drop constraint

CREATE TABLE Employee
(
Id INT NOT NULL,
Name VARCHAR2(100),
CONSTRAINT pk_Emploee_Id PRIMARY KEY (Id)
);

ALTER TABLE Employee
DROP CONSTRAINT pk_Emploee_Id
;

Alter table to add multiple columns

ALTER TABLE Employee
CREATE Table Employee
(
Id int PRIMARY KEY ,
Name VARCHAR2(100)
);

ADD
(
Email VARCHAR2(50),
Mobile VARCHAR2(20)
);