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From:Rocio Gomez Escribano Date:May 3 2011 6:08am
Subject:independent tables
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Everyone has his/her own driving license, and I need to know what kind of
“person” (client or user) is.

 

 

mysql> select userID, clientID from client, user where
(clientCodeDrivingLicense= 321321321 || userCodeDrivingLicense = 321321321);

+--------+-------+

| userID | clientID |

+--------+-------+

|      1 |     2 |

|      2 |     2 |

|      3 |     2 |

|      4 |     2 |

|      5 |     2 |

+--------+-------+

5 rows in set (0.00 sec)

 

But, what I want is something like that:

 

     +--------+-------+

     | userID | clientID |

     +--------+-------+

     |      Null |     2 |

     +--------+-------+

 

I tried something like this:

 

select COUNT(DISTINCT u.userID), userID, clientID from client, user  where
(clientCodeDrivingLicense = 321321321 || userCodeDrivingLicense =
321321321);

+--------------------------+--------+-------+

| COUNT(DISTINCT u.userID) | userID | clientID |

+--------------------------+--------+-------+

|                        5 |      1 |     2 |

+--------------------------+--------+-------+

1 row in set (0.00 sec)

 

But it wont be efficient enough in the future.

 

I suppose my solution is an Join, but they have no intersection, so, I cant
imagine how do it

 

Thank you!!

 

Regards

 

 

 

 

 

Rocío Gómez Escribano

 <mailto:r.sanchez@stripped> r.gomez@stripped

 

Descripción: cid:image002.jpg@stripped

Polígono Campollano C/F, nº21T

02007 Albacete (España)

Tlf:967-504-513  Fax: 967-504-513

www.ingenia-soluciones.com

 


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independent tablesRocio Gomez Escribano3 May