[SOLVED] Query question.. (no errors, wrong results)

[ruben-]

Database contains:

 

tblBuildings:

---------------

| buildingId  |

|  1          |

|  2          |

|  3          |

---------------

 

tblBuildingsRequirements:

------------------------------------

| buildingId  | requiredBuildingId |

|  2       |        1          |

|  3       |        1          |

------------------------------------

 

tblUsersBuildings

------------------------

| userid  | buildingId |

|  1      |    1      |

------------------------

 

 

Query I try to run:

SELECT * FROM tblBuildings B

WHERE

(

  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR

  JOIN tblUsersBuildings UB ON UB.buildingId = BR.requiredBuildingId

  WHERE BR.buildingId = B.buildingId

  AND UB.userId = 1

)

=

(

  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR WHERE BR.buildingId = B.buildingId

)

 

 

What am I trying to do?

Select all the buildings which requirements have been met, so this query *should* return:

----------------

| buildingId=1 |

| buildingId=2 |

| buildingId=3 |

----------------

But it returns:

----------------

| buildingId=1 |

----------------

 

 

My logic in my query:

 

;;;  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR

;;;  JOIN tblUsersBuildings UB ON UB.buildingId = BR.requiredBuildingId

;;;  WHERE BR.buildingId = B.buildingId

;;;  AND UB.userId = 1

 

This part of the query should count how many buildings are required for the building "B.buildingId"

Join it with the buildings that are actually build by user "1", and count how many there are left,

so if a user built all the buildings, this count should say as many as the next count:

 

 

;;; SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR WHERE BR.buildingId = B.buildingId

 

This part counts how many buildings are required by the building with id: B.buildingId

 

 

 

Some testing:

;;;  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR

;;;  JOIN tblUsersBuildings UB ON UB.buildingId = BR.requiredBuildingId

;;;  WHERE BR.buildingId = 2

;;;  AND UB.userId = 1

Returns 1

 

;;; SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR WHERE BR.buildingId = 2

Returns 1

 

So I really have no idea why it doesnt work in the real query..

 

 

WITHOUT THE COUNT() IT RETURNS:

buildingId=2

buildingId=3

 

[ruben-]

My code works if I use:

 

  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR 
  WHERE BR.buildingId = B.buildingId 
  AND EXISTS
  (
  SELECT * FROM tblUsersBuildings UB 
  WHERE UB.buildingId = BR.requiredBuildingId 
  AND UB.userId = 1
  )

 

in stead of:

  SELECT COUNT(BR.buildingId) FROM tblBuildingsRequirements BR
  JOIN tblUsersBuildings UB ON UB.buildingId = BR.requiredBuildingId
  WHERE BR.buildingId = B.buildingId
  AND UB.userId = 1

 

But if it's a join, and the row doesn't exist, it doesn't show up? Does it? So the results should be the same :\

[ruben-]

http://bugs.mysql.com/bug.php?id=27363