Assuming none of the sought values can ever occur more than once for
each dicentry (untested):

select d.id, d.whateverfieldsyouwanttooutput
from dicentries d
inner join dskrptlink_dicentries link
on link.id_dicentry = d.id
inner join dskrpts
on dskrpts.id = link.id_dskrpt
where dskrpts.asdskrpt in ('abc', 'def', 'ghi')
group by d.id, d.whateverfieldsyouwanttooutput
having count(*) >= 3

If the sought values can occur multiple times and you want to return
those where each sought value occurs at least once:

select d.id, d.whateverfieldsyouwanttooutput
from dicentries d
inner join dskrptlink_dicentries link
on link.id_dicentry = d.id
inner join dskrpts
on dskrpts.id = link.id_dskrpt
where dskrpts.asdskrpt in ('abc', 'def', 'ghi')
group by d.id, d.whateverfieldsyouwanttooutput
having count(distinct dskrpts.asdskrpt) = 3

Kjell

martinknappe wrote:

> thanx, the links did make join clearer but now i'm wondering whether
> join is indeed the right tool to get my query right (maybe my table
> structure is just a bit too extravagant for a beginner; dunno); see,
> join as i understand is useful to fetch fields from various tables at
> a time and into the same result set, right?
> now, actually, i don't want that..in my query i only want to fetch
> fields from one table (dicentries) only the selection criterion for
> which records to pick makes the query so long
>
> imagine three tables as follows(only search-relevant fields mentioned):
>
> dicentries.id (primary key)
> dskrptlink_dicentries.id_dicentry (foreign key on field above)
> dskrptlink_dicentries.id_dskrpt (foreign key on field below)
> dskrpts.id (primary key)
> dskrpts.asdskrpt (search-relevant string)
>
> as this makes clear, a record in dicentries can have various
> corresponding records in dskrpts
> now, the user of my app would enter one or more such search-relevant
> strings(e.g.: 'abc', 'def', and 'ghi') into the mask after which a
> query should be generated fetching all those records from dicentries
> which are linked VIA table dskrptlink_dicentries to all of the
> following three records in dskrpts:
>
> r1: dskrpts.asdskrpt = 'abc'
> r2: dskrpts.asdskrpt = 'def'
> r3: dskrpts.asdskrpt = 'ghi'
>
> would someone please show me how to formulate this particular example
> in a time-efficient query just to put me on the right track?
>
> thanx,
>
> martin
>
>
>
> --- In firebird-support@yahoogroups.com, "Martijn Tonies"
> <m.tonies@...> wrote:
>
>>
>>
>>>ok, i figure the answer to my initial question is then no..i've read
>>>about 'join' before but i never got too familiar with it so i just
>>>stuck to composing my sql-queries of combinations of "select * from
>>>(select ...)"-statements because i thought join was only there for the
>>>sake of readability (which i don't really care about) but if it really
>>>makes my search faster then it seems i'd indeed better do some reading
>>>up :-)
>>
>>Well, let me explain a bit more ...
>>
>>In the ideal case of a DBMS, you don't have to tell it "how" to get your
>>data, but only "what". This is part of the whole idea behind a DBMS.
>>
>>Between your application and the physical data (on disk), there's a
>
> whole
>
>>series of layers.
>>
>>One of these, is called an "optimizer". What this should do, is turn
>
> your
>
>>query (whatever it is, JOINs, SELECT FROM ( SELECT FROM )) into
>>something that it thinks is the most efficient way of getting your data.
>>
>>In theory, this works fine.
>>
>>In practice, it's very hard to write an optimizer that's fool proof with
>>regard to what uses to get your data AND to make it fast.
>>
>>So, in theory, both a well-written JOIN statement and yours should
>>be able to return the same data in pretty much the same time.
>>
>>In practice, it's more common to write a query statement that's readable
>>and as short as possible in order to simply the optimizers job.
>>
>>
>>That being said, the SQL language has several constructs to do what
>>you want to get as a result. Read up on JOIN and get to understand
>>what it does, it's very useful.
>>
>>Here's a quick online reference:
>>http://www.w3schools.com/sql/default.asp
>>
>>
>>Martijn Tonies
>>Database Workbench - development tool for Firebird and more!
>>Upscene Productions
>>http://www.upscene.com
>>My thoughts:
>>http://blog.upscene.com/martijn/
>>Database development questions? Check the forum!
>>http://www.databasedevelopmentforum.com
>>
>
>
>
>
>
>
>
>
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> Visit http://firebird.sourceforge.net and click the Resources item
> on the main (top) menu. Try Knowledgebase and FAQ links !
>
> Also search the knowledgebases at http://www.ibphoenix.com
>
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

--
--------------------------------------
Kjell Rilbe
Adressmarknaden AM AB
E-post: kjell.rilbe@...
Telefon: 08-761 06 55
Mobil: 0733-44 24 64