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Posted by J.O. Aho on 11/02/05 19:33
Pugi! wrote:
> "J.O. Aho" <user@example.net> schreef in bericht
> news:3ss896Fpjj4pU1@individual.net...
>> Pugi! wrote:
>>> I have problem with sql statement.
>>> I have made a address-database, problem is concerning getting information
>>> out of it.
>>> Because for not everyone in my address-db I have all that information I
>>> created the table lnk_ent_comm
>>> When I query database for a certain entity I get all the types of how to
>>> communicate with him/her/it that are available. But I would also like to
>>> see
>>> the types/means of communication that are missing for which there is no
>>> entry in table lnk_ent_comm
>>> I tried a left join from table communication on lnk_ent_comm, but that
>>> doesn't work.
>>
>>
>> Join your communication table to the lnk_ent_comm table and search for the
>> user id_entity and where lnk_ent_comm.value is NULL.
>
> How do u do that? Could u give example ? Remember there are no null values
> in lnk_ent_comm.
SELECT * FROM communication LEFT JOIN lnk_ent_comm ON
communication.id = lnk_ent_comm.id_communication WHERE lnk_ent_comm.id_entity
= 54 AND lnk_ent_comm IS NULL
//Aho
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