Selection with a random Column : RAND « Function « SQL / MySQL






  1. SQL / MySQL
  2. Function
  3. RAND

Selection with a random Column

     
mysql>
mysql>
mysql> CREATE TABLE titles (
    ->   titleID int(11),
    ->   title varchar(100),
    ->   subtitle varchar(100),
    ->   edition tinyint(4),
    ->   publID int(11),
    ->   catID int(11),
    ->   langID int(11),
    ->   year int(11),
    ->   isbn varchar(20),
    ->   comment varchar(255),
    ->   ts timestamp,
    ->   authors varchar(255),
    ->   PRIMARY KEY  (titleID)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql>
mysql>
mysql> INSERT INTO titles VALUES (1,'Linux','Installation',5,1,57,2,2000,NULL,NULL,'2005-02-28 13:34:21','Michael'),
    ->                           (2,'Excel',NULL,NULL,2,3,NULL,2000,NULL,NULL,'2005-02-28 13:34:22','David'),
    ->                           (3,'XML',NULL,NULL,1,2,NULL,1997,NULL,NULL,'2005-02-28 13:34:22','Edwards'),
    ->                           (4,'PHP',NULL,NULL,3,6,NULL,2000,NULL,NULL,'2005-02-28 13:34:22','Tom'),
    ->                           (5,'MySQL','',0,3,34,NULL,2000,'','','2005-02-28 13:34:22','Paul'),
    ->                           (6,'Java',NULL,NULL,4,34,NULL,1999,NULL,NULL,'2005-02-28 13:34:22','Tim');
Query OK, 6 rows affected (0.00 sec)
Records: 6  Duplicates: 0  Warnings: 0

mysql>
mysql>
mysql> ALTER TABLE titles ADD random DOUBLE;
Query OK, 6 rows affected (0.01 sec)
Records: 6  Duplicates: 0  Warnings: 0

mysql>
mysql> ALTER TABLE titles ADD INDEX (random);
Query OK, 6 rows affected (0.01 sec)
Records: 6  Duplicates: 0  Warnings: 0

mysql>
mysql> UPDATE titles SET random = RAND();
Query OK, 6 rows affected (0.00 sec)
Rows matched: 6  Changed: 6  Warnings: 0

mysql>
mysql> SELECT titleID, title FROM titles
    -> WHERE random > RAND() ORDER BY random LIMIT 1;
+---------+-------+
| titleID | title |
+---------+-------+
|       6 | Java  |
+---------+-------+
1 row in set (0.00 sec)

mysql>
mysql> drop table titles;
Query OK, 0 rows affected (0.00 sec)








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