Re: multi table multi database join?
From: Patrice (nobody_at_nowhere.com)
Date: 03/23/05
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Date: Wed, 23 Mar 2005 12:26:16 +0100
What I had in mind is :
- on a single server you can do a join between several tables in distinct
databases without any problem
- you could also do this using a "linked server" allowing to perform joins
between the target server and the linked server
- finally you could do get the data from each server seperately and
establish the relation in ADO.NET
You mentionned also you would require a huge amount of memory. Do you need
all those data at once ? Generally we attempt to load in the datatable the
minimal amount of data currently needed ie.e instead of loading all the
records for the whole county, the query should likely retrieve results based
on some kind of user criteria (the user is unlikely to browse all records, I
suppose he pick a record based on some ID or search criteria).
Hope it gives some ideas...
Patrice
-- "gabriel" <anonymous@discussions.microsoft.com> a écrit dans le message de news:043c01c52f8d$d7c87520$a401280a@phx.gbl... do you always answer questions with questions? (löl, i appreciate the help) dont i have some kind of filter? a filter for what? i dont understand your question. Are they on the same server? no.., yes.., sometimes. sybase runns on one machine mssql on another, what would it change if they were runningon the same machine (aside from degrading their performance while they are each under load). we have several counties with this setup, each has its own particular, ..mmm... particulars. what will i do with all those records?, i dont think i'm talking about a large set of records in output maybe 10 to 100 (that doesnt seem like much), i dunno what i'd do with them. skip around them by the campfire at first, no seriously, they'll be used in various billing, appointment scheduling, medical treatment trending routines. the setup is county wide health information. maybe 200 clinics per county, each clinic has its data in its own (sybase) db, then the finiancial parts of the individual sybase dbs are combined into a mssql db for each county. (the other parts of the individual sybase dbs arent laid out to be combined) some reports are run from the aggregated db. more reports would be possible if some of the data from the aggregate db could be used in a query to a specific (sybase) db. but this is just one example., cant you add tables from multiple sources into an MSaccess project, then run a query that joins fields from each of the those tables even if the tables are in databases on seperate machines? (honest question, i dunno), this is basically my question, is that possible in ado.net? if its possible how would it be done without first pulling over each of the tables into a datatable and then linking the tables? >-----Original Message----- >Are they on the same serve r? Which server ? > >Also it's quite unusual to retrieve this. Don't you have some kind of filter >? What do you do with all those records ? > >Patrice > >-- > >"gabriel" <anonymous@discussions.microsoft.com> a écrit dans le message de >news:11ba01c52f7e$eabe1e00$a501280a@phx.gbl... >> i'd like to execute a query that joins tables from >> seperate databases. i think i could pull this off by >> first running a query to each database into seperate >> datatables, then adding joins to the tables, but this >> seems like it may require stupidly huge memory as in some >> cases i'm running a query on tables that store the medical >> records for entire countys. >> is there a better way with ado.net? >> >> (i'm using obdc.net to access sybase ase 12.5 and sql 2000 >> thru preconfigured dsns) >> thanks in advance >> g > > >. >
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