How to Create a Database in SQL

CREATE DATABASE OFFICE;
USE OFFICE;
CREATE TABLE Employees
(
Employee_id varchar(10) primary key not null,
Employee_Name char(20)not null,
Employee_Address varchar(30) not null,
Employee_Mobileno varchar(10) not null
);
select * from Employees
insert into Employees values ('K112','Krishna', 'Mahipalpur New Delhi-37',9540434299);
insert into Employees values ('S211','Surbhi','Palam new delhi');
insert into Employees values ('v311','mansi','palam new delhi');
alter table employees ADD Employee_mobileno varchar(10);
update Employees set Employee_Mobileno=9540434299 where Employee_id='K111';