MySQL Tutorial/Table Join/Cross Join
CROSS JOIN the linking table
mysql>
mysql>
mysql> CREATE TABLE Books(
-> BookID SMALLINT NOT NULL PRIMARY KEY,
-> BookTitle VARCHAR(60) NOT NULL,
-> Copyright YEAR NOT NULL
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.03 sec)
mysql>
mysql>
mysql> INSERT INTO Books VALUES (12786, "Java", 1934),
-> (13331, "MySQL", 1919),
-> (14356, "PHP", 1966),
-> (15729, "PERL", 1932),
-> (16284, "Oracle", 1996),
-> (17695, "Pl/SQL", 1980),
-> (19264, "JavaScript", 1992),
-> (19354, "www.sqle.ru", 1993);
Query OK, 8 rows affected (0.02 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> CREATE TABLE Authors(
-> AuthID SMALLINT NOT NULL PRIMARY KEY,
-> AuthFN VARCHAR(20),
-> AuthMN VARCHAR(20),
-> AuthLN VARCHAR(20)
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.03 sec)
mysql>
mysql>
mysql> INSERT INTO Authors VALUES (1006, "H", "S.", "T"),
-> (1007, "J", "C", "O"),
-> (1008, "B", NULL, "E"),
-> (1009, "R", "M", "R"),
-> (1010, "J", "K", "T"),
-> (1011, "J", "G.", "N"),
-> (1012, "A", NULL, "P"),
-> (1013, "A", NULL, "W"),
-> (1014, "N", NULL, "A");
Query OK, 9 rows affected (0.05 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> CREATE TABLE AuthorBook(
-> AuthID SMALLINT NOT NULL,
-> BookID SMALLINT NOT NULL,
-> PRIMARY KEY (AuthID, BookID),
-> FOREIGN KEY (AuthID) REFERENCES Authors (AuthID),
-> FOREIGN KEY (BookID) REFERENCES Books (BookID)
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.03 sec)
mysql>
mysql>
mysql> INSERT INTO AuthorBook VALUES (1006, 14356),
-> (1008, 15729),
-> (1009, 12786),
-> (1010, 17695),
-> (1011, 15729),
-> (1012, 19264),
-> (1012, 19354),
-> (1014, 16284);
Query OK, 8 rows affected (0.03 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> select * from Authors;
+--------+--------+--------+--------+
| AuthID | AuthFN | AuthMN | AuthLN |
+--------+--------+--------+--------+
| 1006 | H | S. | T |
| 1007 | J | C | O |
| 1008 | B | NULL | E |
| 1009 | R | M | R |
| 1010 | J | K | T |
| 1011 | J | G. | N |
| 1012 | A | NULL | P |
| 1013 | A | NULL | W |
| 1014 | N | NULL | A |
+--------+--------+--------+--------+
9 rows in set (0.00 sec)
mysql> select * from Books;
+--------+----------------+-----------+
| BookID | BookTitle | Copyright |
+--------+----------------+-----------+
| 12786 | Java | 1934 |
| 13331 | MySQL | 1919 |
| 14356 | PHP | 1966 |
| 15729 | PERL | 1932 |
| 16284 | Oracle | 1996 |
| 17695 | Pl/SQL | 1980 |
| 19264 | JavaScript | 1992 |
| 19354 | www.sqle.ru | 1993 |
+--------+----------------+-----------+
8 rows in set (0.00 sec)
mysql> select * from AuthorBook;
+--------+--------+
| AuthID | BookID |
+--------+--------+
| 1009 | 12786 |
| 1006 | 14356 |
| 1008 | 15729 |
| 1011 | 15729 |
| 1014 | 16284 |
| 1010 | 17695 |
| 1012 | 19264 |
| 1012 | 19354 |
+--------+--------+
8 rows in set (0.01 sec)
mysql>
mysql> SELECT BookTitle, AuthID FROM Books CROSS JOIN AuthorBook;
+----------------+--------+
| BookTitle | AuthID |
+----------------+--------+
| Java | 1006 |
| MySQL | 1006 |
| PHP | 1006 |
| PERL | 1006 |
| Oracle | 1006 |
| Pl/SQL | 1006 |
| JavaScript | 1006 |
| www.sqle.ru | 1006 |
| Java | 1008 |
| MySQL | 1008 |
| PHP | 1008 |
| PERL | 1008 |
| Oracle | 1008 |
| Pl/SQL | 1008 |
| JavaScript | 1008 |
| www.sqle.ru | 1008 |
| Java | 1009 |
| MySQL | 1009 |
| PHP | 1009 |
| PERL | 1009 |
| Oracle | 1009 |
| Pl/SQL | 1009 |
| JavaScript | 1009 |
| www.sqle.ru | 1009 |
| Java | 1010 |
| MySQL | 1010 |
| PHP | 1010 |
| PERL | 1010 |
| Oracle | 1010 |
| Pl/SQL | 1010 |
| JavaScript | 1010 |
| www.sqle.ru | 1010 |
| Java | 1011 |
| MySQL | 1011 |
| PHP | 1011 |
| PERL | 1011 |
| Oracle | 1011 |
| Pl/SQL | 1011 |
| JavaScript | 1011 |
| www.sqle.ru | 1011 |
| Java | 1012 |
| MySQL | 1012 |
| PHP | 1012 |
| PERL | 1012 |
| Oracle | 1012 |
| Pl/SQL | 1012 |
| JavaScript | 1012 |
| www.sqle.ru | 1012 |
| Java | 1012 |
| MySQL | 1012 |
| PHP | 1012 |
| PERL | 1012 |
| Oracle | 1012 |
| Pl/SQL | 1012 |
| JavaScript | 1012 |
| www.sqle.ru | 1012 |
| Java | 1014 |
| MySQL | 1014 |
| PHP | 1014 |
| PERL | 1014 |
| Oracle | 1014 |
| Pl/SQL | 1014 |
| JavaScript | 1014 |
| www.sqle.ru | 1014 |
+----------------+--------+
64 rows in set (0.00 sec)
mysql>
mysql> drop table AuthorBook;
Query OK, 0 rows affected (0.02 sec)
mysql> drop table Books;
Query OK, 0 rows affected (0.05 sec)
mysql> drop table Authors;
Query OK, 0 rows affected (0.03 sec)
Three-table CROSS JOIN
mysql>
mysql>
mysql> CREATE TABLE Books(
-> BookID SMALLINT NOT NULL PRIMARY KEY,
-> BookTitle VARCHAR(60) NOT NULL,
-> Copyright YEAR NOT NULL
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.06 sec)
mysql>
mysql>
mysql> INSERT INTO Books VALUES (12786, "Java", 1934),
-> (13331, "MySQL", 1919),
-> (14356, "PHP", 1966),
-> (15729, "PERL", 1932),
-> (16284, "Oracle", 1996),
-> (17695, "Pl/SQL", 1980),
-> (19264, "JavaScript", 1992),
-> (19354, "www.sqle.ru", 1993);
Query OK, 8 rows affected (0.03 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> CREATE TABLE Authors(
-> AuthID SMALLINT NOT NULL PRIMARY KEY,
-> AuthFN VARCHAR(20),
-> AuthMN VARCHAR(20),
-> AuthLN VARCHAR(20)
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.03 sec)
mysql>
mysql>
mysql> INSERT INTO Authors VALUES (1006, "H", "S.", "T"),
-> (1007, "J", "C", "O"),
-> (1008, "B", NULL, "E"),
-> (1009, "R", "M", "R"),
-> (1010, "J", "K", "T"),
-> (1011, "J", "G.", "N"),
-> (1012, "A", NULL, "P"),
-> (1013, "A", NULL, "W"),
-> (1014, "N", NULL, "A");
Query OK, 9 rows affected (0.05 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> CREATE TABLE AuthorBook(
-> AuthID SMALLINT NOT NULL,
-> BookID SMALLINT NOT NULL,
-> PRIMARY KEY (AuthID, BookID),
-> FOREIGN KEY (AuthID) REFERENCES Authors (AuthID),
-> FOREIGN KEY (BookID) REFERENCES Books (BookID)
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.05 sec)
mysql>
mysql>
mysql> INSERT INTO AuthorBook VALUES (1006, 14356),
-> (1008, 15729),
-> (1009, 12786),
-> (1010, 17695),
-> (1011, 15729),
-> (1012, 19264),
-> (1012, 19354),
-> (1014, 16284);
Query OK, 8 rows affected (0.03 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> select * from Authors;
+--------+--------+--------+--------+
| AuthID | AuthFN | AuthMN | AuthLN |
+--------+--------+--------+--------+
| 1006 | H | S. | T |
| 1007 | J | C | O |
| 1008 | B | NULL | E |
| 1009 | R | M | R |
| 1010 | J | K | T |
| 1011 | J | G. | N |
| 1012 | A | NULL | P |
| 1013 | A | NULL | W |
| 1014 | N | NULL | A |
+--------+--------+--------+--------+
9 rows in set (0.00 sec)
mysql> select * from Books;
+--------+----------------+-----------+
| BookID | BookTitle | Copyright |
+--------+----------------+-----------+
| 12786 | Java | 1934 |
| 13331 | MySQL | 1919 |
| 14356 | PHP | 1966 |
| 15729 | PERL | 1932 |
| 16284 | Oracle | 1996 |
| 17695 | Pl/SQL | 1980 |
| 19264 | JavaScript | 1992 |
| 19354 | www.sqle.ru | 1993 |
+--------+----------------+-----------+
8 rows in set (0.00 sec)
mysql> select * from AuthorBook;
+--------+--------+
| AuthID | BookID |
+--------+--------+
| 1009 | 12786 |
| 1006 | 14356 |
| 1008 | 15729 |
| 1011 | 15729 |
| 1014 | 16284 |
| 1010 | 17695 |
| 1012 | 19264 |
| 1012 | 19354 |
+--------+--------+
8 rows in set (0.00 sec)
mysql>
mysql> SELECT BookTitle, Copyright, CONCAT_WS(" ", AuthFN, AuthMN, AuthLN) AS Author
-> FROM Books AS b CROSS JOIN AuthorBook AS ab ON b.BookID=ab.BookID
-> CROSS JOIN Authors AS a ON ab.AuthID=a.AuthID
-> WHERE Copyright<1980
-> ORDER BY BookTitle;
+-----------+-----------+--------+
| BookTitle | Copyright | Author |
+-----------+-----------+--------+
| Java | 1934 | R M R |
| PERL | 1932 | B E |
| PERL | 1932 | J G. N |
| PHP | 1966 | H S. T |
+-----------+-----------+--------+
4 rows in set (0.00 sec)
mysql>
mysql> drop table AuthorBook;
Query OK, 0 rows affected (0.05 sec)
mysql> drop table Books;
Query OK, 0 rows affected (0.05 sec)
mysql> drop table Authors;
Query OK, 0 rows affected (0.05 sec)