Access/Network mechanics ???

[Sean]

Hi all,

I'm wondering, for a while now,

Access front end, tables are ODBC linked to SQL Server backend

scenario 1 select * from LARGE table (say 300,000) records) (should
return 300,000 records right???)

scenario 2 select * fron LARGE table where PrimaryKey = 777 (should
return 1 record right???)

Does anybody know how it all works or where I can read the answers..

I'd like to know how many records are being being dragged acrosss the
network in various situations.

ALSO,
If I have a form/subform arrangement and the subform is master/child linked
to the main form, then how many records are coming across the network???

thanks in advance..

Obviously being aware of this must help in appl development..

 

[david epsom dot com dot au]

Hi all,

I'm wondering, for a while now,

Access front end, tables are ODBC linked to SQL Server backend

scenario 1 select * from LARGE table (say 300,000) records)
return 300,000 records right???)

Depends what kind of curser you are using. Even when you select
all 300,000 records, you may only get a set of pointers to those
records. In Access, this was called a 'Dynaset'.

scenario 2 select * fron LARGE table where PrimaryKey = 777
return 1 record right???)

Right. But Access has the ability to use User Defined Functions,
written in VB, in SQL. UDF's can only be evaluated in Access,
and any data required must be loaded. So if you have SQL like:
SELECT * from LARGE table where MyFunction(PrimaryKey) = True;
then all of the PrimaryKey values must be loaded so that
MyFunction can be evaluated for each one.

Does anybody know how it all works or where I can read the answers..

I'd like to know how many records are being being dragged acrosss the
network in various situations.

You can TRACE your ODBC connections