To select a single winner from each table and combine the results : Union « Select Clause « SQL / MySQL






  1. SQL / MySQL
  2. Select Clause
  3. Union

To select a single winner from each table and combine the results

      
mysql>
mysql>
mysql> CREATE TABLE prospect
    -> (
    ->  fname   CHAR(40),
    ->  lname   CHAR(40),
    ->  addr    CHAR(40)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> CREATE TABLE customer
    -> (
    ->  last_name       CHAR(40),
    ->  first_name      CHAR(40),
    ->  address CHAR(40)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> CREATE TABLE vendor
    -> (
    ->  company CHAR(60),
    ->  street  CHAR(30)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> INSERT INTO prospect (fname, lname, addr)
    ->  VALUES
    ->          ('Peter','Jones','482 Main St., Apt. 402'),
    ->          ('Bernice','Smith','916 Maple Dr.')
    -> ;
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql>
mysql> INSERT INTO customer (first_name, last_name, address)
    ->  VALUES
    ->          ('Grace','Peterson','16055 First Ave.'),
    ->          ('Bernice','Smith','916 Maple Dr.'),
    ->          ('Walter','Brown','8602 1st St.')
    -> ;
Query OK, 3 rows affected (0.00 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql>
mysql> INSERT INTO vendor (company, street)
    ->  VALUES
    ->          ('Database, Inc.','38 Third Ave.'),
    ->          ('Xml, Ltd.','213B Commerce Park.')
    -> ;
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql>
mysql>
mysql> (SELECT CONCAT(lname,', ',fname) AS name, addr
    -> FROM prospect ORDER BY RAND( ) LIMIT 1)
    -> UNION
    -> (SELECT CONCAT(last_name,', ',first_name), address
    -> FROM customer ORDER BY RAND( ) LIMIT 1)
    -> UNION
    -> (SELECT company, street
    -> FROM vendor ORDER BY RAND( ) LIMIT 1);
+---------------+------------------------+
| name          | addr                   |
+---------------+------------------------+
| Jones, Peter  | 482 Main St., Apt. 402 |
| Brown, Walter | 8602 1st St.           |
| Xml, Ltd.     | 213B Commerce Park.    |
+---------------+------------------------+
3 rows in set (0.00 sec)

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

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

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

mysql>








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