Define foreign key : Foreign Key : Key SQL / MySQL


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Define foreign key



Drop table Books;
Drop table Authors;
Drop table AuthorBook;


CREATE TABLE Books (
   BookID SMALLINT NOT NULL PRIMARY KEY,
   BookTitle VARCHAR(60NOT NULL,
   Copyright YEAR NOT NULL
)
ENGINE=INNODB;

INSERT INTO Books VALUES (1'Letters', 1934),
                         (2'Ohio', 1919),
                         (3'Angels', 1966),
                         (4'Speaks', 1932),
                         (5'Man', 1996),
                         (6'A'1980),
                         (7'Card', 1992),
                         (8'The', 1993);

CREATE TABLE Authors (
   AuthID SMALLINT NOT NULL PRIMARY KEY,
   AuthFN VARCHAR(20),
   AuthMN VARCHAR(20),
   AuthLN VARCHAR(20)
)
ENGINE=INNODB;

INSERT INTO Authors VALUES (1'Henry', 'S.', 'Thompson'),
                           (2'Jack', 'Carol', 'Oates'),
                           (3'Red', NULL, 'Elk'),
                           (4'White', 'Maria', 'Rilke'),
                           (5'Anne', 'Kennedy', 'Toole'),
                           (6'Jane', 'G.', 'Neihardt'),
                           (7'Jane', NULL, 'Yin'),
                           (8'Alan', NULL, 'Wang');

CREATE TABLE AuthorBook (
   AuthID SMALLINT NOT NULL,
   BookID SMALLINT NOT NULL,
   PRIMARY KEY (AuthID, BookID),
   FOREIGN KEY (AuthIDREFERENCES Authors (AuthID),
   FOREIGN KEY (BookIDREFERENCES Books (BookID)
)
ENGINE=INNODB;

INSERT INTO AuthorBook VALUES (18)
                              (27)
                              (36)
                              (45),
                              (54)
                              (62)
                              (81);



           
       



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