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Overview of Data Access MacDonald Ch. 15 MIS 324 Professor Sandvig Overview ADO.NET overview Datasets & Datatables Data Access Displaying data Web Controls ADO.NET Overview “Any web application worth writing involves data access.” Stephen Walther ADO ActiveX Data Objects Microsoft’s data access technologies Set of classes that provide data access services Class Library System.Data ADO.NET Overview Data sources include: relational databases XML files Web Services Text files, etc… Goal loose coupling between data source and application minimize dependencies DataSet & DataTable Dataset is object for holding data Central feature of ADO.NET Provides tools for working with data DataSet is a collection of DataTables Relationships between tables Data Sources: Web Controls: Relational database XML file Web Service Text file etc… Dataset (data tables) List controls Tabular controls Navigation controls DataSet & DataTable Provides many capabilities of relational database Relationships Keys Referential integrity Dataviews: sort and filtering Change history Data stored as XML Behind the scenes .NET Data options 1. Programmatically Use connection & command objects 2. Very flexible approach Similar to PHP Data Source Controls 3. Pass SQL to database Drag & drop in Visual Studio Declarative approach Easy but inflexible Added in .NET 2.0 Entity Framework Creates objects representing database structure Query with SQL or Entity SQL Added to .NET 3.5 Retrieving Data MIS 324 Will use programmatic approach Benefits Flexible Uses standard OOP programming techniques MIS 424 Data Source Controls Entity Framework Displaying Data Steps: 1. Retrieve data from datasource 2. Fill DataTable 3. “Bind” to web control a. b. c. List controls (1 column) Tabular controls (>1 column) Single record controls B. Displaying Data Bind datatable to web control Web Controls List Controls Tabular Controls Single record controls Example: source, output Summary ADO.NET 1. 2. Dataset Memory resident data container Bind to Web Controls Web Controls Classes that handle data access Provides consistent programming interface to data sources Write HTML & data to client Next: SQL Server Express Creating databases & using with ASP.NET