Question

I have the following two tables:

system
- id
- systemName
- idOrganization

organization
- id
- officeSymbol

I am running the following query and receiving an id is ambiguous error:

SELECT system.systemName, organization.officeSymbol
FROM system
LEFT JOIN (organization)
ON (system.idOrganization = organization.id)

As you can see, I’m not selecting the id column. If I place system.id within the list of fields to select, I no longer receive this error. Unfortunately, the manner in which this data is handled I can’t return the id – we don’t want it displayed to the user.

Also, if I add GROUP BY system.systemName I no longer get the error – but this just doesn’t seem like the optimal solution.

Note: The LEFT JOIN is intentional as not all systems will be assigned to an Organization.

SELECT VERSION()
--> 5.0.77-community-log

CREATE TABLE system (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `systemName` VARCHAR(45) DEFAULT NULL,
  `idOrganization` INT(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_system_organization` (`idOrganization`),
  CONSTRAINT `fk_system_organization` 
    FOREIGN KEY (`idOrganization`) 
    REFERENCES `organization` (`id`) 
    ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE organization (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `officeSymbol` VARCHAR(45) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Answer 1

Tested on 5.0.77:

SELECT  VERSION();

VERSION()
5.0.77


CREATE TABLE organization (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `officeSymbol` VARCHAR(45) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE system (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `systemName` VARCHAR(45) DEFAULT NULL,
  `idOrganization` INT(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_system_organization` (`idOrganization`),
  CONSTRAINT `fk_system_organization`
    FOREIGN KEY (`idOrganization`)
    REFERENCES `organization` (`id`)
    ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT
INTO   organization
VALUES
        (1, 'Organization 1'),
        (2, 'Organization 2');
INSERT
INTO     system
VALUES  (1, 'System 1', 1),
        (2, 'System 2', 2);
SELECT  system.systemName, organization.officeSymbol
FROM    system
LEFT JOIN
        (organization)
ON      (system.idOrganization = organization.id);

systemName      officeSymbol
System 1        Organization 1
System 2        Organization 2

Everything works fine.

Note that LEFT JOIN is useless here, since you have a FOREIGN KEY to organization, and there will always be an organization for every given system.

In your comment to @Artem Barger‘s post you said:

I’m only selecting on 5 of the 42 fields shared between these 2 tables

Is it that there are other fields in the tables and/or query?

Since you have a syntactic error, every comma may matter.