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Introduction to Database Processing with ADO.NET

Introduction to Database Processing with ADO.NET. The ASP.NET / ADO.NET Conundrum. The tools and wizards are wonderful for simple applications As applications become more complex and “real” You need to write code between the controls and the data providers

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Introduction to Database Processing with ADO.NET

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  1. Introduction to Database Processing with ADO.NET

  2. The ASP.NET / ADO.NET Conundrum • The tools and wizards are wonderful for simple applications • As applications become more complex and “real” • You need to write code between the controls and the data providers • Nested controls and one-to-many views become complex • At some point, the visual designers become useless

  3. Lecture Overview • Introduce ASP.NET data sources • Introduce the ASP.NET data bound controls • Show a few SIMPLE examples to get us started

  4. History of ADO (1) • Open Database Connectivity (ODBC) was created to provide a uniform API to access SQL database servers • OLE DB evolved from ODBC and provided a COM based interface • Next came the first versions of ADO, which encapsulated OLE DB • ADO.NET is the current generation of ADO and uses .NET Managed Providers

  5. History of ADO (2) • While not a problem Microsoft has stepped away from all MSAccess support. • The data controls are gone • Necessary Jet versions are not usually installed

  6. ADO / ASP.NET NOTE • The capabilities of ASP and ADO are vast • There are many ways to accomplish the same task • DataReaders vs. DataAdapters • DataSource controls vs. manual binding • Bound control configuration is sophisticated

  7. ADO.NET -The Role of Managed Providers • Managedproviders interact with a data source and return data to an application • Data sources are typically (almost always) disconnected • After data is returned to the application, connections are closed

  8. ADO.NET Namespaces / Classes (Intro) • There are many of these • Some you don’t need to work with directly • There are many ways to accomplish the same task • Mastery of the topic requires that you understand what the controls do and how they interact with the underlying classes

  9. ADO.NET Namespaces (1) • Here’s the fabric • System.Data • System.Data.SqlClient • System.Data.OleDb • System.Data.SqlTypes

  10. ADO.NET Classes (1) • Connection – creates the connection with the data source (database) • Support is provided for ORACLE, SQL Server, Access, etc. • Transaction – allows for transactional processing • Command – typically an SQL statement executed against a database server • Parameter – a parameter passed to a command

  11. ADO.NET Classes (2) • DataAdapter – a database object that returns a disconnected set of records (DataSet and DataTable) • DataReader – a forward-only reader to get database records

  12. Introduction to Connections • Executing a database command is generally a two-step process • Create a connection • Prepare and execute a command • The ASP.NET controls help automate much of the process • There are specific connection classes for OLE DB, SQL Server and others • They all work the same way

  13. Connection Strings • There are tools to build these for you based on the database provider • Connection strings are typically stored in the web.config file • They store all information needed to establish a database connection • More later

  14. Connection Strings (Example) • Connection strings are usually stored in web.config • The following reads the connection string from web.config

  15. Connection Strings (Example) • The SqlConnectionobject represents the connection itself. It’s properties depict the connection status

  16. Executing Commands(Introduction) • Use the SqlCommand object to • Return one record one field (ExecuteNonQuery) • Execute SQL INSERT, UPDATE, DELETE statements • Return records in the form of a DataTable • Return records one row at a time (DataReader)

  17. SqlCommand Object (Using 1 row) • The OleDbCommand or SqlCommandobjects work the same way • Set the CommandText property to the SQL statement to execute • Set the CommandType property to CommandType.Text • Set the Connection property to an existing Connection object

  18. SqlCommand Object (Using 1 row) • To return one field from one row, call ExecutScalar() on the SqlCommandobject

  19. SqlCommand Object (Returning Nothing) • Use the ExecuteNonQuerymethod to execute SQL statements that do not return values • INSERT / UPDATE / DELETE • As before, the CommandText property stores the SQL statement • Two ways to do INSERT / UPDATE /DELETE • With parameters • Roll the statement by hand

  20. SqlCommand Object (Returning Nothing - Manual) • Use create the CommandText, CommandType and Connection as before • The INSERT / UPDATE / DELETE statements get contorted

  21. SqlCommand Object (Parameters 1 ) • Parameters provide the preferred way to pass data to INSERT / UPDATE / DELETE and other SQL statements • Parameters begin with an @ in the SQL statement

  22. SqlCommand Object (Parameters 1 ) • Then we create the parameters as part of the command object • We are adding items to the parameters collection

  23. Using the DataReader • This is straight out of the book • There are much better ways to read data but here is the first cut • It’s a forward only reader • Call Read to read the first and subsequent records • Create an SqlCommand object as before • Call ExecuteReader to initialize • Call Read to read each record • Index contains the field name

  24. Using the DataReader (example)

  25. Reading Multiple Records • Here, we use the DataSet and DataTableobjects along with the DataAdapter • Steps • Create SqlCommand with the SELECT statement as before • Create a new SqlDataAdapter • Create a DataSet • Call Fill on the DataAdapter to populate the DataSet

  26. Reading Multiple Records

  27. Introduction to Data Sources • Data sources establish the connection between an ASP.NET application and a database • These are not the same controls as the desktop controls

  28. Data Source Controls(Categories) • Tabular • AccessDataSource – For Access databases • SqlDataSource – For SQL databases • ObjectDataSource – For custom business objects • Hierarchical • SiteMapDataSource – For menus • XmlDataSource – To bind XML documents

  29. Data Sources (Core Concepts) • The ASP.NET data source controls are bound to a page rather than the application • They belong to System.Web rather than System.Data so they are again unique to ASP.NET • Underneath the hood, there is a DataSet • You can use the System.Data classes from an ASP.NET application • Visual Studio does a great job configuring the data source controls

  30. Data Sources (Under the Hood 1) • The Wizards configure properties to • Write SELECT statements and customize them • Write INSERT, UPDATE, and DELETE statements that are executed by other bound controls

  31. Data Sources(Under the Hood 2) • The Properties window tells thetale

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