outher joins formats

Hi

I work ith sql server 2000 and i need know the diferent
of joins in format not ansi ( with * ) and joins in format
ansi ( with 'outher join on' ).

Two format work equal ?

What is de correct format ?

Thank you.

R.ragaza@.ozu.es (raulgz) wrote in message news:<9b551742.0403040208.51bb41d1@.posting.google.com>...
> Hi
> I work ith sql server 2000 and i need know the diferent
> of joins in format not ansi ( with * ) and joins in format
> ansi ( with 'outher join on' ).
>
> Two format work equal ?
>
> What is de correct format ?
>
> Thank you.
>
> R.

You should always use the ANSI syntax, because the 'old style' joins
are unclear, and some queries cannot be written at all with them. In
addition, Microsoft may stop supporting the old syntax in a future
version of MSSQL.

In an outer join, you need to separate the join condition (in the JOIN
clause) from the filter conditions (in the WHERE clause) to make sure
you get consistent results. In the old style join, all the conditions
are together in the WHERE clause, so the database engine has to
'guess' at what you meant, and the results may not be what you want.

This KB article shows the difference:

http://support.microsoft.com/defaul...0&Product=sql2k

Simon|||Read more about this by downloading SQL books online free from
http://www.microsoft.com/sql

INNER JOIN FORMATS (only identical rows)

select *
from tablea, tableb
where tablea.id = tableb.id

select *
from tablea inner join tableb
on tablea.id = tableb.id

RIGHT OUTER JOIN FORMATS (all rows on right, shows null on left where no
match)

select *
from tablea, tableb
where tablea.id =* tableb.id

SELECT *
from tablea right outer join tableb
on tablea.id = tableb.id

LEFT OUTER JOIN FORMATS (all rows on left, shows null on right where no
match)

select *
from tablea, tableb
where tablea.id *= tableb.id

SELECT *
from tablea left outer join tableb
on tablea.id = tableb.id

FULL OUTER JOIN FORMATS ( shows null where no match)

Select *
from tablea, tableb
where tablea.id FULL OUTER JOIN tableb.id

Select *
from tablea, tableb
where tablea.id FULL JOIN tableb.id

CROSS JOINS (cross product, all possible combinations)

select *
from tablea, tableb

select *
from tablea cross join tableb

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OUTER JOIN table limit?

I came across this statement from ASP.NET forum : "..There is a limit to the level for OUTER JOIN ANSI SQL limit is four after that you may get strange results. ..." . I did a little research but without getting clear answer from the SQL92 standard itself. I am wondering whether I can get help about this in SQL Server 2005 implementation here.

I put this question in another way, How many tables can we use in OUTER JOIN(or INNER JOIN) in SQL Server 2005?

Thanks.

There is no limit in the ANSI SQL standard or SQL Server. In fact, the ANSI SQL standard doesn't talk about such limits anywhere. They provide specifications on the syntax and how it should work etc. Note that a particular database implementation can have limits imposed. SQL Server 2005 for example has a maximum limit of 256 table references in a SELECT statement. So you can end up in some situation where the query optimizer cannot produce a plan due to insufficient resources in the system if the query is too complex and contains large number of table references. See below example for SQL Server 2005 which allows more than 4 outer joins:

with t(i)
as (
select 1
)
select *
from t as t1
left join t as t2
left join t as t3
left join t as t4
left join t as t5
left join t as t6
left join t as t7
left join t as t8
left join t as t9
left join t as t10
on t10.i = t9.i
on t9.i = t8.i
on t8.i = t7.i
on t7.i = t6.i
on t6.i = t5.i
on t5.i = t4.i
on t4.i = t3.i
on t3.i = t2.i
on t2.i = t1.i

|||

as far as sql server is concerned there is no limitation.

it could have been a limitation from data access tier

e.g. dataset

|||

Hello:

I was pointed to this "Three-Way Joins and Beyond" in SQL Pperformance Tuning by Peter Gulutzan and Trudy Pelzer.

Can I get some explaination for this statement: "You can expect the DBMS optimizer to start going wrong if five or more joins are in the query (until recently Microsoft's admitted limit was four). "

Is there anything I miss here?

This book was published on September 10, 2002.

Thank you.

|||

That article makes several incorrect assumptions and looks like the authors are not well informed about SQL Server. For example, the support for recognizing transitive predicates has been in the product since SQL Server 7.0. See link below:

http://www.microsoft.com/technet/prodtechnol/sql/70/reskit/part9/sqc13.mspx?mfr=true

I didn't go through all the chapters but the first page itself has several errors and doesn't apply to SQL Server. Performance of joins involving large number of tables can be a problem depending on the resources and the query plan. This has also been improved considerably in the product for every release starting from SQL 6x. If you are looking for querying tips for SQL Server, you may want to look at some of the new Inside SQL Server 2005 series for example.

|||

Hi Umachandar:

Thank you for answering this question. I used multiple outer joins to extract a dataset from my database. That table limit statement could pose a serious problem to my query if it were true for SQL Server 2000 or 2005.

Out Join Syntax

Hello,

I need to write and Ansi Outer Join that has 2 columns from the same table.

I keep getting

Server: Msg 4104, Level 16, State 1, Line 3
The multi-part identifier "dim_person.person_key" could not be bound.

here is what the code looks like. any help is appreciated.

select ...

from dim_day_of_year
, dim_company
, dim_currency
, dim_account
, dim_person
, ods_conference
left outer join fact_usage_alloc fua1 on ods_conference.conf_key=fua1.conf_key
left outer join fact_usage_alloc fua2
on dim_person.person_key=fua2.requestor_person_key

where...from ...
, ods_conference
left outer
join fact_usage_alloc fua
on fua.conf_key = ods_conference.conf_key
and fua.requestor_person_key = dim_person.person_key|||That certainly makes sense to me but produces a syntax error :mad:

left outer join fact_usage_alloc fua
on fua.conf_key=ods_conference.conf_key
and on fua.requestor_person_key=dim_person.person_key
where fua.company_key = dim_company.company_key...........

Thanks for the reply|||you're welcome

you can't say "and on"|||hmmm. Still getting the bind error. I even cut and pasted your example in and I get the same thing. I didn't realize mssql was so particular :S|||okay, here's the deal: re-write your other comma-delimited table joins as INNER JOINs

i bet the error goes away ;)|||Mixing non ansi and ansi forms is just a bad idea

Plus, unless I missing it, your outter join tables don't seem to be joing to anything

Plus, you really should get into good formatting, it will make your like so much easier

SELECT ColumnList
FROM dim_day_of_year a
INNER JOIN dim_company b
ON b.col = ?.col
INNER JOIN dim_currency c
ON c.col = ?.col
INNER JOIN dim_account d
ON d.col =?.col
INNER JOIN dim_person e
ON e.col = ?.col
INNER JOIN ods_conference f
ON f.col = ?.col
LEFT JOIN fact_usage_alloc g
ON e.conf_key = f.conf_key -- This one makes no sense
LEFT JOIN fact_usage_alloc h
ON d.person_ke = g.requestor_person_key -- Nor does this one|||okay, here's the deal: re-write your other comma-delimited table joins as INNER JOINs

i bet the error goes away ;)

You funny

The message you have enetered is too short|||You funnyno, i was serious -- i bet the error goes away because of how the FROM clause is parsed

the explicit JOINS are probably being interpreted first, before being combined with the comma-delimited tables

sort of like * and / are done before + and -

thus, in this local context:
ods_conference
left outer
join fact_usage_alloc fua
on fua.conf_key = ods_conference.conf_key
and fua.requestor_person_key = dim_person.person_keythis explains the error message -- "dim_person.person_key" could not be bound

dim_person hasn't been parsed as a table yet|||Thanks for the effort guys. This was a quick test to see how easy it would be to convert a legacy system to MSSQL. I think we got a portion of the answer.

Thanks Again.sql