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Posted by J.O. Aho on 11/02/05 23:27
Pugi! wrote:
> "J.O. Aho" <user@example.net> schreef in bericht
> news:3ssbbuFppjkrU1@individual.net...
>> 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
>
> If I run it as above I get error : #1054 - Unknown column 'lnk_ent_comm' in
> 'where clause'.
> If I add a valid columname like value : query returns nothing.
sorry, but it should have been lnk_ent_comm.value
//Aho
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