 	CONSTRAINT pk_sections PRIMARY KEY ( id )
  );
 
-CREATE INDEX idx_sections ON departments ( leader );
-
-CREATE TABLE employees ( 
+CREATE INDEX idx_sections ON department ( leader );
+
+CREATE TABLE employee ( 
 	id                   serial  NOT NULL,
 	name                 varchar(200)  NOT NULL,
 	address              varchar(300)  NOT NULL,

CREATE TABLE classes (
	id                   serial  NOT NULL,
	name                 varchar(100)  NOT NULL,
	base_price           numeric(8,2)  ,
	CONSTRAINT pk_classes PRIMARY KEY ( id )
 );

COMMENT ON TABLE classes IS 'Different types of room standard';

COMMENT ON COLUMN classes.base_price IS 'Base price is only an information for setting price for a particular room.';

CREATE TABLE notification_types ( 
	id                   serial  NOT NULL,
	name                 varchar(200)  NOT NULL,
	CONSTRAINT pk_notification_types PRIMARY KEY ( id )
 );

CREATE TABLE order_categories ( 
	id                   serial  NOT NULL,
	name                 varchar(200)  NOT NULL,
	price                numeric(8,2)  ,

	CONSTRAINT pk_payments PRIMARY KEY ( id )
 );

CREATE INDEX idx_payments ON payment ( id_order );

CREATE TABLE reservation ( 
	id                   serial  NOT NULL,
	id_room              integer  NOT NULL,
	id_guest             integer  NOT NULL,
