Joining tables in different databases
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From: MC on 24 Jan 2006 10:04 Agreed, but why not provide a more complete info since theres a little difference? He may need to pull data from two servers tomorrow... MC "Tom Moreau" <tom(a)dont.spam.me.cips.ca> wrote in message news:LBqBf.4368$ft2.109590(a)news20.bellglobal.com... > The OP said the two DB's were on the same server. Therefore, 3-part > naming > is sufficient. > > -- > Tom > > ---------------------------------------------------- > Thomas A. Moreau, BSc, PhD, MCSE, MCDBA > SQL Server MVP > Columnist, SQL Server Professional > Toronto, ON Canada > www.pinpub.com > > "MC" <marko_culo#@#yahoo#.#com#> wrote in message > news:dr5cc8$bue$1(a)magcargo.vodatel.hr... > Try 'four part names' :). > server.database.owner.table > > > MC > > > "Captain Nemo" <nemo(a)nospam.com> wrote in message > news:6oqBf.8267$wl.3901(a)text.news.blueyonder.co.uk... >> Hi >> >> I'm working on an ASP project where the clients want to be able to >> effectively perform SELECT queries joining tables from two different >> databases (located on the same SQL-Server). >> >> Does this involve creating virtual tables that link to another database, >> or >> am I completely on the wrong track? >> >> Any hints as to where I might find more information (buzz-words, etc.) >> would >> be most appreciated. >> >> Thanks >> >> > > >
From: Tom Moreau on 24 Jan 2006 11:45 There's often a performance difference. -- Tom ---------------------------------------------------- Thomas A. Moreau, BSc, PhD, MCSE, MCDBA SQL Server MVP Columnist, SQL Server Professional Toronto, ON Canada www.pinpub.com "MC" <marko_culo#@#yahoo#.#com#> wrote in message news:dr5eu2$s5q$1(a)magcargo.vodatel.hr... Agreed, but why not provide a more complete info since theres a little difference? He may need to pull data from two servers tomorrow... MC "Tom Moreau" <tom(a)dont.spam.me.cips.ca> wrote in message news:LBqBf.4368$ft2.109590(a)news20.bellglobal.com... > The OP said the two DB's were on the same server. Therefore, 3-part > naming > is sufficient. > > -- > Tom > > ---------------------------------------------------- > Thomas A. Moreau, BSc, PhD, MCSE, MCDBA > SQL Server MVP > Columnist, SQL Server Professional > Toronto, ON Canada > www.pinpub.com > > "MC" <marko_culo#@#yahoo#.#com#> wrote in message > news:dr5cc8$bue$1(a)magcargo.vodatel.hr... > Try 'four part names' :). > server.database.owner.table > > > MC > > > "Captain Nemo" <nemo(a)nospam.com> wrote in message > news:6oqBf.8267$wl.3901(a)text.news.blueyonder.co.uk... >> Hi >> >> I'm working on an ASP project where the clients want to be able to >> effectively perform SELECT queries joining tables from two different >> databases (located on the same SQL-Server). >> >> Does this involve creating virtual tables that link to another database, >> or >> am I completely on the wrong track? >> >> Any hints as to where I might find more information (buzz-words, etc.) >> would >> be most appreciated. >> >> Thanks >> >> > > >
From: MC on 25 Jan 2006 03:41 Do you mean that actually specifing servername slows down the query? Could you explain why? MC "Tom Moreau" <tom(a)dont.spam.me.cips.ca> wrote in message news:dRsBf.4433$ft2.115520(a)news20.bellglobal.com... > There's often a performance difference. > > -- > Tom > > ---------------------------------------------------- > Thomas A. Moreau, BSc, PhD, MCSE, MCDBA > SQL Server MVP > Columnist, SQL Server Professional > Toronto, ON Canada > www.pinpub.com > > "MC" <marko_culo#@#yahoo#.#com#> wrote in message > news:dr5eu2$s5q$1(a)magcargo.vodatel.hr... > Agreed, but why not provide a more complete info since theres a little > difference? He may need to pull data from two servers tomorrow... > > > MC > > > "Tom Moreau" <tom(a)dont.spam.me.cips.ca> wrote in message > news:LBqBf.4368$ft2.109590(a)news20.bellglobal.com... >> The OP said the two DB's were on the same server. Therefore, 3-part >> naming >> is sufficient. >> >> -- >> Tom >> >> ---------------------------------------------------- >> Thomas A. Moreau, BSc, PhD, MCSE, MCDBA >> SQL Server MVP >> Columnist, SQL Server Professional >> Toronto, ON Canada >> www.pinpub.com >> >> "MC" <marko_culo#@#yahoo#.#com#> wrote in message >> news:dr5cc8$bue$1(a)magcargo.vodatel.hr... >> Try 'four part names' :). >> server.database.owner.table >> >> >> MC >> >> >> "Captain Nemo" <nemo(a)nospam.com> wrote in message >> news:6oqBf.8267$wl.3901(a)text.news.blueyonder.co.uk... >>> Hi >>> >>> I'm working on an ASP project where the clients want to be able to >>> effectively perform SELECT queries joining tables from two different >>> databases (located on the same SQL-Server). >>> >>> Does this involve creating virtual tables that link to another database, >>> or >>> am I completely on the wrong track? >>> >>> Any hints as to where I might find more information (buzz-words, etc.) >>> would >>> be most appreciated. >>> >>> Thanks >>> >>> >> >> >> > > > >
From: Erland Sommarskog on 25 Jan 2006 17:47 MC (marko_culo#@#yahoo#.#com#) writes: > Do you mean that actually specifing servername slows down the query? Could > you explain why? If the server name use is @@servername, SQL Server will shortcut, and there is no overhead. But if the linked server is defined a true loopback, so that there is a new connection made, there is obviously an overhead, as data is first passed to SQL Server, to the OLE DB provider on one connection, and then the OLE DB provider passes the data back to another connection. -- Erland Sommarskog, SQL Server MVP, esquel(a)sommarskog.se Books Online for SQL Server 2005 at http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx Books Online for SQL Server 2000 at http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
From: MC on 26 Jan 2006 02:25 Thank you for that, I assumed engine would 'optimize' that and never checked. Just when I think I actually know something ;)..... MC "Erland Sommarskog" <esquel(a)sommarskog.se> wrote in message news:Xns9756F1F84A0F4Yazorman(a)127.0.0.1... > MC (marko_culo#@#yahoo#.#com#) writes: >> Do you mean that actually specifing servername slows down the query? >> Could >> you explain why? > > If the server name use is @@servername, SQL Server will shortcut, and > there is no overhead. > > But if the linked server is defined a true loopback, so that there is a > new connection made, there is obviously an overhead, as data is first > passed to SQL Server, to the OLE DB provider on one connection, and then > the OLE DB provider passes the data back to another connection. > > -- > Erland Sommarskog, SQL Server MVP, esquel(a)sommarskog.se > > Books Online for SQL Server 2005 at > http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx > Books Online for SQL Server 2000 at > http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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