BUILDING THE DATA ACCESS LAYER in .NET framework

Draw QR Code 2d barcode in .NET framework BUILDING THE DATA ACCESS LAYER
8 BUILDING THE DATA ACCESS LAYER
QR Code 2d Barcode Drawer In Visual Studio .NET
Using Barcode maker for .NET Control to generate, create QR-Code image in Visual Studio .NET applications.
Figure 816 The References tab in the Project Designer for the DAC de nes the references to the NET Framework database libraries
QR Code 2d Barcode Reader In .NET Framework
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET framework applications.
8
Bar Code Maker In .NET
Using Barcode maker for .NET framework Control to generate, create bar code image in .NET framework applications.
Building the Data Access Layer
Barcode Decoder In Visual Studio .NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in .NET framework applications.
At this point, decide which data provider you will use in your DAC and import its associated library using the Imported Namespaces list shown in Figure 816 The common data providers and their associated libraries are:
QR Code Encoder In C#
Using Barcode drawer for .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.
For SQL Server, import the SystemDataSqlClient namespace For Access using OleDb, import the SystemDataOleDb namespace For any ODBC data source, import the SystemDataOdbc namespace To support any data source from any data provider, import the SystemDataCommon namespace
QR Code Drawer In VS .NET
Using Barcode printer for ASP.NET Control to generate, create Quick Response Code image in ASP.NET applications.
If you select one of the rst three options, the code in the DAC is basically the same; only the library names are different If you select the last option, you need to implement the DbProviderFactory, which is a little more complex and beyond the scope of this book See the Additional Reading section for more information Your DAC project is then ready You can then add all of the code required to access data as described in the next sections
Encoding QR In Visual Basic .NET
Using Barcode printer for VS .NET Control to generate, create Denso QR Bar Code image in VS .NET applications.
Building Along
Making UCC - 12 In VS .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Universal Product Code version A image in .NET applications.
For the Purchase Tracker sample application: Visual Studio created a default class for you when you created the data access component Class Library project (PTDAC) in 3 In Solution Explorer, change the name of this default class from Class1 to DAC This is the class that contains all of the data access code Add a reference to the SystemData namespace, and import both the SystemData and SystemDataSqlClient namespaces NOTE: This Building Along assumes that you are using SQL Server If you are using Access, you need to reference the SystemDataOleDb namespace instead of SystemDataSqlClient At this point, there is no code in your data access component yet, so there are no new features to try out
European Article Number 13 Drawer In .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create EAN 13 image in .NET applications.
Building a Data Access Component
Barcode Generation In .NET Framework
Using Barcode printer for .NET Control to generate, create barcode image in VS .NET applications.
Defining the Connection String
UCC - 12 Generator In .NET Framework
Using Barcode drawer for .NET Control to generate, create UCC.EAN - 128 image in Visual Studio .NET applications.
Before the code in your application can access a database, it needs to connect to the database That is normally done using a connection string A connection string is a concatenated set of connection parameters that is used by NET Framework database library methods to connect to the database Connection strings are not easy to de ne The information in a connection string depends on the type of connection in a rather complex way The best way to get the correct set of information for your connection string is to use Server Explorer To view the correct connection string for your database: 1 Open Server Explorer (View | Server Explorer) 2 Right-click the data connection and select Modify Connection from the context menu This displays the Modify Connection dialog 3 Click the Advanced button at the bottom of the dialog The Advanced Properties dialog displays the valid connection string at the bottom of the dialog, as shown in Figure 817
Encode 4-State Customer Barcode In VS .NET
Using Barcode maker for Visual Studio .NET Control to generate, create OneCode image in Visual Studio .NET applications.
8 BUILDING THE DATA ACCESS LAYER
Draw ECC200 In .NET
Using Barcode maker for ASP.NET Control to generate, create Data Matrix 2d barcode image in ASP.NET applications.
Figure 817 The Advanced Properties dialog for the connection displays the connection string used to connect to the database You can select and copy it to the Clipboard to ensure that you have a valid connection string
Scanning EAN / UCC - 13 In .NET Framework
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
8
Bar Code Encoder In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create barcode image in ASP.NET applications.
Building the Data Access Layer
Code 39 Full ASCII Generator In Visual Basic .NET
Using Barcode creation for Visual Studio .NET Control to generate, create Code-39 image in VS .NET applications.
NOTE: The connection string for an Access database looks very different For example:
Bar Code Drawer In Java
Using Barcode drawer for Java Control to generate, create bar code image in Java applications.
Provider=MicrosoftJetOLEDB40; Data Source="C:\Data\PTMDB"
Creating UPC Code In .NET Framework
Using Barcode creator for ASP.NET Control to generate, create GTIN - 12 image in ASP.NET applications.
Once you have a valid connection string, you need to put it somewhere in the application The easiest place to de ne the connection string is in the application settings Recall from 4, Building the User Interface Layer, that there are two types of application settings: user-scoped and applicationscoped 4 detailed user-scoped settings to store each form s last user-de ned location and size at runtime Connection strings use application-scoped settings Application-scoped settings are associated with the application, so users cannot change them at runtime To set the connection string in the application settings: 1 Open the Project Designer for the DAC Class Library project Right-click the project in Solution Explorer and select Properties from the context menu, or select Project | Properties from the main menu bar, or double-click on the My Project folder under the project in Solution Explorer to open the Project Designer 2 Select the Settings tab 3 In the Name column, enter the logical name for the connection string 4 In the Type column, select (Connection string) as the type for the setting 5 In the Scope column, select Application scope 6 Enter the connection string in the Value column If you copied it from the prior dialog, you can paste it here The result is shown in Figure 818 All settings are stored in the appcon g le You can view the settings by opening the appcon g le for the project in which you de ned the application setting
Generating Code 3 Of 9 In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create Code 3/9 image in ASP.NET applications.
Barcode Generator In VS .NET
Using Barcode drawer for ASP.NET Control to generate, create barcode image in ASP.NET applications.