text: -- for help             \?
  -- list database's      \l
  -- create database      CREATE DATABASE database_name
  -- list tables          \d
  -- output table         \d table_name
  -- change current db    \c
  -- add column           ALTER TABLE table_name ADD COLUMN featured BOOLEAN
  --remove column         ALTER TABLE table_name DROP COLUMN featured
  
  /* create table 
  create table restaurant (
      id int,
      name varchar(50),
      location varchar(50),
      price_range int
  );
  */
  INSERT INTO restaurant (id, name, location, price_range) values (124, 'pizza hut', 'wyoming', 2)
  
  create table restaurant (
      id bigserial NOT NULL PRIMARY KEY,
      name varchar(50) NOT NULL,
      location varchar(50) NOT NULL,
      price_range INT NOT NULL check(price_range >= 1 and price_range <= 5)
  );
  
  INSERT INTO restaurant (name, location, price_range) values ('pizza hut', 'wyoming', 2)
  