Mysql学习mysql子查询使用EXISTS命令的例子

/*
mysql> SELECT ArticleID, ArticleTitle
    -> FROM Articles AS b
    -> WHERE EXISTS
    ->    (
    ->       SELECT ArticleID
    ->       FROM AuthorArticle AS ab
    ->       WHERE b.ArticleID=ab.ArticleID
    ->    )
    -> ORDER BY ArticleTitle;
+-----------+-------------------+
| ArticleID | ArticleTitle      |
+-----------+-------------------+
|     19354 | AI                |
|     15729 | Buy a paper       |
|     16284 | Conferences       |
|     12786 | How write a paper |
|     19264 | Information       |
|     17695 | Journal           |
|     14356 | Sell a paper      |
+-----------+-------------------+
7 rows in set (0.01 sec)
*/      
Drop table Articles;
Drop table Authors;
Drop table AuthorArticle;MYSQL应用

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

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);MYSQL应用

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

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');MYSQL应用

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

INSERT INTO AuthorArticle VALUES (1006, 14356),
                              (1008, 15729),
                              (1009, 12786),
                              (1010, 17695),
                              (1011, 15729),
                              (1012, 19264),
                              (1012, 19354),
                              (1014, 16284);
 MYSQL应用

SELECT ArticleID, ArticleTitle
FROM Articles AS b
WHERE EXISTS
   (
      SELECT ArticleID
      FROM AuthorArticle AS ab
      WHERE b.ArticleID=ab.ArticleID
   )
ORDER BY ArticleTitle;