Many to many select needed

Paer Toernell
Paer Toernell used Ask the Experts™
on
I have one database with owners, one with property and one with links (relations). Each row in links tell what owner is connected to what property. More than one owner can share one property. But do i make a select of all the property one owner have, and how do i make a select of what owners that share a particular property?

Questions One:  What property's does "Bill" own?
Question Two: Who are the owners of "Red Scorpion"?

-- Definition for database test6534465
--
DROP DATABASE IF EXISTS test6534465;
CREATE DATABASE test6534465
	CHARACTER SET utf8
	COLLATE utf8_general_ci;

-- 
-- Disable foreign keys
-- 
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;

-- 
-- Set SQL mode
-- 
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;

-- 
-- Set default database
--
USE test6534465;

--
-- Definition for table links
--
CREATE TABLE links (
  idLink INT(11) NOT NULL AUTO_INCREMENT,
  idowner INT(11) DEFAULT NULL,
  idproperty INT(11) DEFAULT NULL,
  PRIMARY KEY (idLink)
)
ENGINE = INNODB
AUTO_INCREMENT = 5
AVG_ROW_LENGTH = 4096
CHARACTER SET utf8
COLLATE utf8_general_ci;

--
-- Definition for table owners
--
CREATE TABLE owners (
  idowner INT(11) NOT NULL AUTO_INCREMENT,
  nameowner VARCHAR(50) DEFAULT NULL,
  PRIMARY KEY (idowner)
)
ENGINE = INNODB
AUTO_INCREMENT = 5
AVG_ROW_LENGTH = 4096
CHARACTER SET utf8
COLLATE utf8_general_ci;

--
-- Definition for table property
--
CREATE TABLE property (
  idproperty INT(11) NOT NULL AUTO_INCREMENT,
  propertyname VARCHAR(255) DEFAULT NULL,
  PRIMARY KEY (idproperty)
)
ENGINE = INNODB
AUTO_INCREMENT = 6
AVG_ROW_LENGTH = 3276
CHARACTER SET utf8
COLLATE utf8_general_ci;

-- 
-- Dumping data for table links
--
INSERT INTO links VALUES
(1, 1, 2),
(2, 1, 3),
(3, 2, 2),
(4, 3, 2);

-- 
-- Dumping data for table owners
--
INSERT INTO owners VALUES
(1, 'Bill'),
(2, 'Angus'),
(3, 'Orrin'),
(4, 'Scott');

-- 
-- Dumping data for table property
--
INSERT INTO property VALUES
(1, 'Blue Car'),
(2, 'Red Scorpion'),
(3, 'Green Bicycle'),
(4, 'ThunderBlue'),
(5, 'OldFan');

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Ryan ChongSoftware Team Lead

Commented:
looks very like a homework to me? the idea is to join the relevant tables so that you can retrieve the info you needed...
Software Team Lead
Commented:
To answer your first and second questions, perhaps you can have a consolidated query result, so from this result you can derive to get the results you want....

Select
b.nameowner, c.propertyname
from links a
inner join owners b on a.idowner = b.idowner
inner join property c on a.idproperty = c.idproperty
order by b.nameowner, c.propertyname

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Put in the "where" clause into SQL above should manage to resolve your 2 questions

Author

Commented:
Nope, its not homework :) Creating a CRM "ish" system to hold some document together. Have been away from programming 3 years, forgot about joins.  I check Your solution tomorrow. Looks great.

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