Mega Code Archive
Addition of the LEFT keyword to each join definition
<![CDATA[
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 (0.01 sec)
mysql>
mysql> INSERT INTO Books VALUES
-> (12786, 'Notebook', 1934),
-> (13331, 'C++', 1919),
-> (14356, 'Opera', 1966),
-> (15729, 'Sql Server', 1932),
-> (16284, 'C', 1996),
-> (17695, 'Pascal', 1980),
-> (19264, 'Postcards', 1992),
-> (19354, 'Oracle', 1993);
Query OK, 8 rows affected (0.00 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 (0.00 sec)
mysql>
mysql> INSERT INTO Authors VALUES
-> (1006, 'Hunter', 'S.', 'Thompson'),
-> (1007, 'Joyce', 'Carol', 'Oates'),
-> (1008, 'Black', NULL, 'Elk'),
-> (1009, 'Rainer', 'Maria', 'Rilke'),
-> (1010, 'John', 'Kennedy', 'Toole'),
-> (1011, 'John', 'G.', 'Neihardt'),
-> (1012, 'Annie', NULL, 'Proulx'),
-> (1013, 'Alan', NULL, 'Watts'),
-> (1014, 'Nelson', NULL, 'Algren');
Query OK, 9 rows affected (0.00 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql> CREATE TABLE AuthorBook
-> (
-> BookID SMALLINT NOT NULL,
-> AuthID SMALLINT NOT NULL,
-> PRIMARY KEY (AuthID, BookID)
-> )
-> ENGINE=INNODB;
Query OK, 0 rows affected (0.00 sec)
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 (0.00 sec)
Records: 8 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql>
mysql> SELECT BookTitle, Copyright,
-> CONCAT_WS(' ', AuthFN, AuthMN, AuthLN) AS Author
-> FROM Books AS b NATURAL LEFT JOIN AuthorBook AS ab
-> NATURAL LEFT JOIN Authors AS a
-> WHERE Copyright<1980
-> ORDER BY BookTitle;
+------------+-----------+--------+
| BookTitle | Copyright | Author |
+------------+-----------+--------+
| C++ | 1919 | |
| Notebook | 1934 | |
| Opera | 1966 | |
| Sql Server | 1932 | |
+------------+-----------+--------+
4 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql> drop table AuthorBook;
Query OK, 0 rows affected (0.00 sec)
mysql> drop table Authors;
Query OK, 0 rows affected (0.00 sec)
mysql> drop table Books;
Query OK, 0 rows affected (0.00 sec)
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