>>2) When you select with an order by, you should use the subselect.
>I'd expect it to not matter all too much, but unless you wanted to order on
>the subselect (in which case I'd definetely recommend a join), I guess
>you're right in that it could be faster.

>The most important will be to have correct indices. You've already got your
>primary keys, in addition you would most likely need an index for
>SampleDetail.MasterID (and possibly more indices depending on your
>WHERE-clauses).

Bu because SampleDetail.MasterID is a foreign key, I don't need to set up
an index yet, don't I?
I read somewhere that Interbase creates an index automatic for primary,
foreign and unique keys.

Regards,
Jörg

>I generally tend to use JOINs more often than subqueries, but that might be
>because I rarely do need 0 or 1 rows returned from a table (which you would
>require for a subselect).

>Set

>At 14:04 14.02.2001 +0100, you wrote:
>>Hi Jörg
>>
>>I have asked the same question half a year ago in the IBO-Mailinglist.

These

>>are the results in short words:
>>1) When you just do a select without an order by, it doesn't matter, if

you

>>use a Join or a SubSelect.
>>2) When you select with an order by, you should use the subselect.
>>
>>
>>Guido.
>>
>>Jörg Schiemann wrote:
>>
>>> Hi,
>>>
>>> I've a master and a detail table like
>>>
>>> create table "SampleMaster" (
>>> MasterID integer not null primary key,
>>> OrderNo integer not null,
>>> Comment varchar(20),
>>> .
>>> .
>>> .
>>> );
>>>
>>> and
>>>
>>> create table "SampleDetail" (
>>> DetailID integer not null primary key,
>>> MasterID integer not null,
>>> OrderPos integer not null,
>>> quantity integer not null,
>>> .
>>> .
>>> .
>>> constraint fk_MasterID foreign key (MasterID) references SampleMaster
>>> (MasterID)
>>> );
>>>
>>> Is a query with a subquery faster then a joined query if I want all

fields

>>> from the SampleDetail and only OrderNo from SampleMaster?
>>>
>>> TIA
>>>
>>> Jörg Schiemann

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