Posted by apfelsine on 09/15/05 15:06

> Yes, I meant that I tried to create a temporary table, not db, sorry...

this would be accomplished with views. Like I mentioned before
but this may not be a Solution for your problem.

As I know a lot of Select Squences with a lot more Joins
than you need here, I do not believe that your performance-problem
results from the sql statement.
Depending on the server-machine your Database is installed on,
there may be different reasons, why this query takes a long time.

1)Maybe your tables are big. Lets asume each of them has 1 000 000 tuples.
Even then the query should not last (DEPENDING ON YOUR MACHINE)
a "long" time.
If this Machine is for example the whole time working on a 70% level
it slows down everything to death.
If the machine has enough breath to acomplish your query and you are testing
just solely we leave this section ...

2)the dbms tries to optimize sql -queries by itself, to make them faster, if
you want to
optimize more, use only the lines and columns you seek. It makes the whole
thing
a little faster if you simply snip columns and rows that you do not need.

3) it may help with performance to apply indexes to columns that will be
joined

4) Your application is getting all data over network one by one and
everything
slows down. Then its not a database or query -problem

5) use the SQL Profiler to see where the bottleneck is.

If you like, create for each join a view and then simply join the view with
folio
like this for example
-------------------------------------
CREATE VIEW stay_test AS
Select Stay_folio.folio_id from
STAY_FOLIO left outer join STAY
ON
stay_folio.stay_id = stay.stay_id
-----------------------------------
SELECT * FROM
folio LEFT OUTER JOIN stay_test
ON
folio.folio_id = stay_test.folio_id
LEFT OUTER JOIN guest
ON
folio.guest_id = guest.guest_id
-----------------------------------


At the SQL profiler you can view each selection that is made and how long it
takes to get result






>
> Regarding the 3 joins...would putting parenthesis around any of them
> help?
> How are they being processed exactly?
> The first join has a single table reference immediately preceding the
> join statement, but the others cannot (is that correct?)
> What are the next two joins being joined to exacty (since there is no
> table specified before the two join statements?
>
> The tables that I'm joining look like this:
>
> ------FOLIO---------------STAY FOLIO-----------------STAY
> |
> |
> |___________GUEST
>
> All transactions have FOLIO records, but not all transactions have STAY
> FOLIO, STAY, OR GUEST records.
> I need to return all transactions that have a folio record.
>
> This is the syntax I'm using to accomplish this:
>
> mydb.dbo.FOLIO FOLIO
> LEFT OUTER JOIN
> mydb.dbo.STAY_FOLIO STAY_FOLIO
> ON
> FOLIO.folio_id = STAY_FOLIO.folio_id
> LEFT OUTER JOIN
> mydb.dbo.STAY STAY
> ON
> STAY_FOLIO.stay_id = STAY.stay_id
> LEFT OUTER JOIN
> mydb.dbo.GUEST GUEST
> ON
> FOLIO.guest_id = GUEST.guest_id
>
> I don't understand how the order of the joins affects their processing.
> Is there a better way to phrase the joins, given the table
> relationships as outlined above?
>
> Thanks!
>

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