Advanced Topics on Using ADO.NET in ASP.NET Data Binding

8/7/2019 Advanced Topics on Using ADO.NET in ASP.NET Data Binding

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DataGridDataGrid -- Multiple Item SelectionMultiple Item Selection

Functionality: Users select multiple rows byFunctionality: Users select multiple rows bychecking the check box for each row, andchecking the check box for each row, andthen perform an action on the selectedthen perform an action on the selected

items.items.

Add a template column to the DataGrid, putAdd a template column to the DataGrid, puta CheckBox control in its ItemTemplate.a CheckBox control in its ItemTemplate.


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DataGridDataGrid -- Multiple Item SelectionMultiple Item Selection (2)(2)

In the code behind, walk through eachIn the code behind, walk through eachDataGrid item to see if the check box isDataGrid item to see if the check box ischecked; if checked, perform the action.checked; if checked, perform the action.


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DataGridDataGrid -- Multiple Item EditingMultiple Item Editing

FunctionalityFunctionality Data is displayed in editable controls byData is displayed in editable controls by

default.default.

Users make changes in multiple items andUsers make changes in multiple items andthen click a button to commit all changesthen click a button to commit all changesat once.at once.


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DataGridDataGrid -- Multiple Item EditingMultiple Item Editing (2)(2)

Create template columns for editable data.Create template columns for editable data.

Add editable controls in the ItemTemplate.Add editable controls in the ItemTemplate.


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Updating is slightly different in the codeUpdating is slightly different in the codebehind.behind.

When the user clicks the Update button,When the user clicks the Update button,there is no way to keep track of whichthere is no way to keep track of whichcolumns of which rows have been modified.columns of which rows have been modified.

Need to go through each DataGrid item,Need to go through each DataGrid item,extract values from all editable controls, andextract values from all editable controls, andmake updates for all the rows.make updates for all the rows.


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DataGridDataGrid -- Summary RowsSummary Rows

Functionality: DataGrid contains summaryFunctionality: DataGrid contains summaryrows to display partial totals of groupedrows to display partial totals of groupedcolumns.columns.

The sample is based on theThe sample is based on the

Northwind MicrosoftNorthwind Microsoft SQLSQLServerServer database. Thedatabase. TheDataGrid lists all the ordersDataGrid lists all the ordersthat each customer hasthat each customer hasissued in year 1998.issued in year 1998.

For each customer, aFor each customer, asummary row displays thesummary row displays thetotal amount of orders.total amount of orders.An extra row summarizes theAn extra row summarizes thegrand total for all customers.grand total for all customers.


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DataGridDataGrid -- Summary RowsSummary Rows (2)(2)

DataGrid doesnt have the feature forDataGrid doesnt have the feature forsummary; you must insert summary rowssummary; you must insert summary rowsdirectly into the data source before attachingdirectly into the data source before attachingthe data to the grid.the data to the grid.

When rows are being drawn, distinguishWhen rows are being drawn, distinguishsummary rows from ordinary rows, andsummary rows from ordinary rows, andrender the former with different layout andrender the former with different layout andstyle.style.


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The GROUP BY clause of the SELECT statement in TThe GROUP BY clause of the SELECT statement in T--SQLSQLprovides the WITH ROLLUP extension that adds predefinedprovides the WITH ROLLUP extension that adds predefinedsummary rows to the result set.summary rows to the result set.

GROUPING is the TGROUPING is the T--SQL aggregate function that works inSQL aggregate function that works inconjunction with ROLLUP. The use of the GROUPING operatorconjunction with ROLLUP. The use of the GROUPING operatorcauses a new column to be added to the result set. This columncauses a new column to be added to the result set. This columncontains a value of 1 if it is grouped by the ROLLUP operator.contains a value of 1 if it is grouped by the ROLLUP operator.Otherwise, the column takes a value of 0.Otherwise, the column takes a value of 0.

By using a CASE..WHEN..END statement you can merge this newBy using a CASE..WHEN..END statement you can merge this new

column with the grouping column.column with the grouping column.


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The result of the query on the previous slide.The result of the query on the previous slide.


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The DataGrid declaration in HTML view.The DataGrid declaration in HTML view.

In the ItemCreated event handler, detect eachIn the ItemCreated event handler, detect eachsummary row, and modify its layout and style.summary row, and modify its layout and style.


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The item text is set only during theThe item text is set only during theOnItemDataBound event.OnItemDataBound event.

Modifying the text in summary rows must beModifying the text in summary rows must bedone in the OnItemDataBound eventdone in the OnItemDataBound event

handler.handler.


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The final DataGrid.The final DataGrid.


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DataGridDataGrid -- Master/Detail PageMaster/Detail Page

Functionality: Users select an item in theFunctionality: Users select an item in themaster DataGrid, and the details will bemaster DataGrid, and the details will bedisplayed in another DataGrid.displayed in another DataGrid.

Load two tables in the DataSet and create aLoad two tables in the DataSet and create aDataRelation between them.DataRelation between them.


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DataGridDataGrid -- Master/Detail PageMaster/Detail Page (2)(2)

The SelectedIndexChanged event is fired onThe SelectedIndexChanged event is fired onselecting an item in the master DataGrid.selecting an item in the master DataGrid.

In its event handler, get the correspondingIn its event handler, get the correspondingDataRows through the DataRelation, and bindDataRows through the DataRelation, and bind

the rows to the detail DataGrid.the rows to the detail DataGrid.


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Web Data Access StrategyWeb Data Access StrategyDataReaderDataReader oror DataSetDataSet

DataReaderDataReader

Slightly better performance and memorySlightly better performance and memoryusageusage

Data object, by default, is discarded withData object, by default, is discarded witheach round tripeach round tripusing DataAdapter forusing DataAdapter fordata binding is usually recommendeddata binding is usually recommended

Reasons for using DataSetReasons for using DataSet

Working with related tablesWorking with related tables

Exchanging data with other processesExchanging data with other processes

Working with a static set of recordsWorking with a static set of records


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Web Data Access StrategyWeb Data Access StrategyCache DataSet or Reload DataSetCache DataSet or Reload DataSet

Caching DataSetCaching DataSet

Pro: saves trips to the data source.Pro: saves trips to the data source.

Con: consumes memory between roundCon: consumes memory between round

trips; can get out of sync with the datatrips; can get out of sync with the datasource.source.

Scenarios for reloading DataSetScenarios for reloading DataSet

Paging through data: reload the DataSetPaging through data: reload the DataSetto get the next set of records to display.to get the next set of records to display.

Working with very volatile data source.Working with very volatile data source.


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Web Data Access StrategyWeb Data Access StrategyCache on Client or on ServerCache on Client or on Server(2)(2)

Caching on the server: Save the datasetCaching on the server: Save the datasetin Session state, Application state, orin Session state, Application state, orusing a cache.using a cache.

Session is scoped to the current browserSession is scoped to the current browsersession.session.

Application: global storage accessibleApplication: global storage accessiblefrom all pages in the Web application.from all pages in the Web application.

Cache: threadCache: thread--safe application levelsafe application levelglobal storage. Cache manager willglobal storage. Cache manager willremove the leastremove the least--used items if the serverused items if the serverneeds memory or if cached data expires.needs memory or if cached data expires.


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Web Data Access StrategyWeb Data Access StrategyCache on Client or on ServerCache on Client or on Server(3)(3)

Example for using caching sessionExample for using caching session

To store the DataSet in the cache:To store the DataSet in the cache:

To get the DataSet back:To get the DataSet back:


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Web Data Access StrategyWeb Data Access StrategySave DataSet in XML FileSave DataSet in XML File

Doesnt take up server or client resourcesDoesnt take up server or client resources

Takes a relatively long time to serialize andTakes a relatively long time to serialize anddeserialize data.deserialize data.


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Additional ResourcesAdditional Resources

Knowledge Base articlesKnowledge Base articles Q313481Q313481 INFO: Roadmap for Web Forms DataINFO: Roadmap for Web Forms Data

BindingBinding

Q307860Q307860 INFO: ASP.NET Data BindingINFO: ASP.NET Data Binding

OverviewOverview Q305140Q305140 INFO: ASP.NET RoadmapINFO: ASP.NET Roadmap

Q313590Q313590 INFO: Roadmap for ADO.NETINFO: Roadmap for ADO.NET

Other linksOther links

Support WebCast: Microsoft ASP.NET DataGridSupport WebCast: Microsoft ASP.NET DataGridWeb Server ControlWeb Server Control

Support WebCast: Data Binding in ASP.NET WebSupport WebCast: Data Binding in ASP.NET WebFormsForms


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Advanced Topics on Using ADO.NET in ASP.NET Data Binding

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