Join three tables : Simple JOIN « Join « SQL / MySQL

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SQL / MySQL » Join » Simple JOIN 
Join three tables
  
/*
mysql> SELECT ArticleTitle, Copyright, CONCAT_WS(' ', AuthorFirstName, AuthorMid
dleName, AuthorLastName) AS Author
    -> FROM Articles AS b, AuthorArticle AS ab, Authors AS a
    -> WHERE b.ArticleID=ab.ArticleID AND ab.AuthID=a.AuthID AND Copyright<1980
    -> ORDER BY ArticleTitle;
+-------------------+-----------+-------------------+
| ArticleTitle      | Copyright | Author            |
+-------------------+-----------+-------------------+
| Buy a paper       |      1932 | James Elk         |
| Buy a paper       |      1932 | Mary G. Lee       |
| How write a paper |      1934 | Tom M Ride        |
| Sell a paper      |      1966 | Henry S. Thompson |
+-------------------+-----------+-------------------+
4 rows in set (0.00 sec)

mysql>
*/

Drop table Articles;
Drop table Authors;
Drop table AuthorArticle;



CREATE TABLE Articles (
   ArticleID SMALLINT NOT NULL PRIMARY KEY,
   ArticleTitle VARCHAR(60NOT NULL,
   Copyright YEAR NOT NULL
)
ENGINE=INNODB;


INSERT INTO Articles VALUES (12786'How write a paper', 1934),
                            (13331'Publish a paper', 1919),
                            (14356'Sell a paper', 1966),
                            (15729'Buy a paper', 1932),
                            (16284'Conferences', 1996),
                            (17695'Journal', 1980),
                            (19264'Information', 1992),
                            (19354'AI', 1993);


CREATE TABLE Authors (
   AuthID SMALLINT NOT NULL PRIMARY KEY,
   AuthorFirstName VARCHAR(20),
   AuthorMiddleName VARCHAR(20),
   AuthorLastName VARCHAR(20)
)
ENGINE=INNODB;


INSERT INTO Authors VALUES (1006'Henry', 'S.', 'Thompson'),
                           (1007'Jason', 'Carol', 'Oak'),
                           (1008'James', NULL, 'Elk'),
                           (1009'Tom', 'M''Ride'),
                           (1010'Jack', 'K''Ken'),
                           (1011'Mary', 'G.', 'Lee'),
                           (1012'Annie', NULL, 'Peng'),
                           (1013'Alan', NULL, 'Wang'),
                           (1014'Nelson', NULL, 'Yin');


CREATE TABLE AuthorArticle (
   AuthID SMALLINT NOT NULL,
   ArticleID SMALLINT NOT NULL,
   PRIMARY KEY (AuthID, ArticleID),
   FOREIGN KEY (AuthIDREFERENCES Authors (AuthID),
   FOREIGN KEY (ArticleIDREFERENCES Articles (ArticleID)
)
ENGINE=INNODB;


INSERT INTO AuthorArticle VALUES (100614356)
                              (100815729)
                              (100912786)
                              (101017695),
                              (101115729)
                              (101219264)
                              (101219354)
                              (101416284);
  
SELECT ArticleTitle, Copyright, CONCAT_WS(' ', AuthorFirstName, AuthorMiddleName, AuthorLastNameAS Author
FROM Articles AS b, AuthorArticle AS ab, Authors AS a
WHERE b.ArticleID=ab.ArticleID AND ab.AuthID=a.AuthID AND Copyright<1980
ORDER BY ArticleTitle;

           
         
    
  
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16.Using table alias to qualify column name when column names exist
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18.PSEUDONYMS FOR TABLE NAMES
19.Qualify the column name with table name
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