 
 CREATE TABLE user_owns_book
 (
-  user_id			INT         	NOT NULL,
+  user_id			INT         	  NOT NULL,
   isbn       	VARCHAR(13)     NOT NULL,
-  CONSTRAINT user_book_pk
-    PRIMARY KEY (user_id, isbn)
+  CONSTRAINT user_owns_book_user_id_FK
+    FOREIGN KEY (user_id)
+    REFERENCES user (user_id),
+  CONSTRAINT user_owns_book_isbn_FK
+    FOREIGN KEY (isbn)
+    REFERENCES user (book)
 );
 
 CREATE TABLE user_requests_book
 (
   user_id			INT         	      NOT NULL,
-  isbn       	VARCHAR(13)     NOT NULL,
-  CONSTRAINT user_book_pk
-    PRIMARY KEY (user_id, isbn)
+  isbn       	VARCHAR(13)         NOT NULL,
+  CONSTRAINT user_requests_book_user_id_FK
+    FOREIGN KEY (user_id)
+    REFERENCES user (user_id),
+  CONSTRAINT user_requests_book_isbn_FK
+    FOREIGN KEY (isbn)
+    REFERENCES user (book)
 );


CREATE TABLE book
(
  isbn     		VARCHAR(13)     NOT NULL,
  title         	VARCHAR(100)	NOT NULL,
  author        VARCHAR(255) NOT NULL,
  publishers		VARCHAR(100)	NOT NULL,
  publish_date		YEAR			NOT NULL,
  thumbnail_url		VARCHAR(255),			
  CONSTRAINT isbn_pk 
    PRIMARY KEY (isbn)

CREATE TABLE user
(
  user_id           INT             NOT NULL 	AUTO_INCREMENT,
  user_first_name   VARCHAR(50)		  NOT NULL,
  user_last_name    VARCHAR(50)     NOT NULL,
  user_city         VARCHAR(20)		  NOT NULL,
  user_state        VARCHAR(2)      NOT NULL,
  user_email		    VARCHAR(50)		  NOT NULL,
  user_password		  VARCHAR(255)		NOT NULL,
  CONSTRAINT user_pk 
    PRIMARY KEY (user_id),
  CONSTRAINT user_email_unq
