BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  How to get next/prior          BorlandTalk.com Forum Index -> Delphi Databases (dbExpress) View previous topic :: View next topic   Author Message Lasse Guest Posted: Mon Dec 13, 2004 11:29 pm    Post subject: How to get next/prior Hi, I want to retrieve one record at the time from a large table with prior and next. I get the first record easily by using a parameterized TSQLQuery, but how do I do to get the next/prior record now?. If I retrieve all records I can use findkey and prior and next on the ClientDataset, but retrieving all records is not efficient. Does anyone have some tips on how to do this? Thanks, Lasse Back to top Bill Todd Guest Posted: Tue Dec 14, 2004 1:07 am    Post subject: Re: How to get next/prior What database are you using? Since relational databases have no concept of ordinality the only way to get rows in a particular order is by using an ORDER BY clause. Since dbExpress dataset components provide a read only forward only cursor the only way to provide bidirectional scrolling is to load the data into a ClientDataSet. How many rows do you need to scroll through? It might help to know what you are trying to accomplish. -- Bill Todd (TeamB) TeamB cannot answer questions received via email Back to top Lasse Guest Posted: Tue Dec 14, 2004 5:05 am    Post subject: Re: How to get next/prior I am using ms sql 2000, Delphi7. It is a form where the user can retrieve a record by searching and then use the next or prior to step. At the moment I am loading all records into the clientdataset and using findkey, prior, next. Its fast to step back and forward but it starts to take time to load as the number of records is growing and I really only need one record in memory at the time. The number of records I need to scroll through is not so many, the number of records I load to the clientdataset is probably a couple of thousands. Lasse "Bill Todd" <no (AT) no (DOT) com> skrev i meddelandet news:41be3cc0$1 (AT) newsgroups (DOT) borland.com... Quote: What database are you using? Since relational databases have no concept of ordinality the only way to get rows in a particular order is by using an ORDER BY clause. Since dbExpress dataset components provide a read only forward only cursor the only way to provide bidirectional scrolling is to load the data into a ClientDataSet. How many rows do you need to scroll through? It might help to know what you are trying to accomplish. -- Bill Todd (TeamB) TeamB cannot answer questions received via email Back to top Bill Todd Guest Posted: Tue Dec 14, 2004 1:57 pm    Post subject: Re: How to get next/prior You are trying to do something that TClientDataSet and SQL database servers in general where not designed to do well and that is to scroll through a large number of row. Personally, I have never seen a user that wants to look for a record manually by scrolling through more than 100 rows at the most. If the user needs to see the rows that are close to the row he/she is searching for then use a SELECT with a reasonable range in the WHERE clause. For example, if the user searches for a row with a value of 5130 use WHERE AFIELD > 5120 AND AFIELD < 5140. The idea is to fetch a small number of rows with each SELECT and run another SELECT when you need more rows. This is the architecture that SQL database servers were designed to support well. -- Bill Todd (TeamB) TeamB cannot answer questions received via email Back to top Lasse Guest Posted: Tue Dec 14, 2004 10:26 pm    Post subject: Re: How to get next/prior Thank you for the advise! "Bill Todd" <no (AT) no (DOT) com> skrev i meddelandet news:41bef130$1 (AT) newsgroups (DOT) borland.com... Quote: You are trying to do something that TClientDataSet and SQL database servers in general where not designed to do well and that is to scroll through a large number of row. Personally, I have never seen a user that wants to look for a record manually by scrolling through more than 100 rows at the most. If the user needs to see the rows that are close to the row he/she is searching for then use a SELECT with a reasonable range in the WHERE clause. For example, if the user searches for a row with a value of 5130 use WHERE AFIELD > 5120 AND AFIELD < 5140. The idea is to fetch a small number of rows with each SELECT and run another SELECT when you need more rows. This is the architecture that SQL database servers were designed to support well. -- Bill Todd (TeamB) TeamB cannot answer questions received via email Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi Databases (dbExpress) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.