PostgreSQL Alter table add column to existing table

Add column to existing table

How to add column to existing table. Alter syntax and example

Syntax

ALTER TABLE table_name 
ADD COLUMN column_name data_type;

Create table

CREATE SEQUENCE seq_users 
INCREMENT 1 MINVALUE 1 
MAXVALUE 9999999999999999 
START 1 CACHE 1;

CREATE TABLE users(
userid numeric not null 
default nextval('seq_users'::regclass),
username varchar(100),
userpass varchar(250),
usermail varchar(50)  
);    

Example Add column

ALTER TABLE users 
ADD COLUMN address varchar(1000);