Subquery uses an aggregate function to arrive at a value that the outer statement can use : Sub query « Select Clause « SQL / MySQL






  1. SQL / MySQL
  2. Select Clause
  3. Sub query

Subquery uses an aggregate function to arrive at a value that the outer statement can use

       
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 (0.01 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 (0.01 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>
mysql>
mysql> SELECT BookTitle, Copyright
    -> FROM Books
    -> WHERE Copyright<(SELECT MAX(Copyright)-50 FROM Books)
    -> ORDER BY BookTitle;
+------------+-----------+
| BookTitle  | Copyright |
+------------+-----------+
| C++        |      1919 |
| Notebook   |      1934 |
| Sql Server |      1932 |
+------------+-----------+
3 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)

mysql>
mysql>








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