CREATE TABLE USERS
  (
   USER_ID   INT               NOT NULL,
   USER_NAME VARCHAR2(20)      NOT NULL,
   PASSWORD VARCHAR2(100)      NOT NULL,
   IMAGE INT				NOT NULL,
   QUESTION VARCHAR2(100)      NOT NULL,
   ANSWER VARCHAR2(100)        NOT NULL,

   PRIMARY KEY (USER_ID)
  );



  CREATE TABLE Devices
  (
   DEVICE_ID		INT	NOT NULL,
   DEVICE_TYPE	VARCHAR2(30),
   DEVICE_DESCRIPTION	VARCHAR2(100),
   DEVICE_WATTAGE	INT		NOT NULL,

   PRIMARY KEY(DEVICE_ID)
);



  CREATE TABLE SMART_PLUG
  (
   PLUG_ID   INT              NOT NULL,
   USER_ID  INT               NOT NULL,


   PRIMARY KEY (PLUG_ID),
   FOREIGN KEY (USER_ID) REFERENCES USERS
  );


CREATE TABLE USAGE
(

   USE_DATE DATE,
   INSTANT_POW INT,
   TOTAL_POW_USED INT,
   PLUG_ID INT    NOT NULL,
   DEVICE_ID INT NOT NULL,

PRIMARY KEY(PLUG_ID,DEVICE_ID),
FOREIGN KEY(PLUG_ID) REFERENCES SMART_PLUG,
FOREIGN KEY(DEVICE_ID) REFERENCES DEVICES,
);