Enterprise Library step by step series (III): Data Access block-entry

Preface: the configuration application was originally mentioned earlier.ProgramBlock Design. Now I want to write the beginner and advanced sections of each application block, and then write the design article in a unified manner. I hope you can understand it :)

In this article, we will explain how to use data access application blocks to access data and provide relevant diagrams.

I.Data Access Application BlockWhat can we do?

1. Provides best practices;

2. Improve consistency;

3. Improve security;

4. Improve ease of use;

II.Data Access Application BlockUsage:

Here I willDaabIs summarized as a trilogy. Before starting, assume that a new project has been created andWeb. configOrApp. configConfiguration file.

Step 1 Define the Configuration:

1.RunEnterprise Library ConfigurationTools,SelectFile | open applicationOpenApp. configFile

2.Right-clickApplicationAnd selectNew | Data Access Application Block

 

3.We can see thatData Access Application BlockAt the same time,Configuration Application Block. Because all applications are based on configuring application blocks.

4.Modify the Database Name:

 

5.Modify the server name:

 

6.Right-clickSQL connection string, SelectParameterTo create a new parameter:

 

7.Modify the parameter nameUIDAnd modifyValue, Specified Login Name:

 

8.Use the same method to create anotherPassword parameter, NamePWD;ValueIs the logon password:

9.Finally, create a database instance:

 

10.SelectFile | save allCommand to save all:

11. Select Attribute|Generate events|Post-event command line Enter the following content:

Copy " $ (Projectdir) \ *. config "   " $ (Targetdir) "

Step 2 Create a database instance:

There are two ways to create a database instance: one is the default database instance, and the other is to map a named instance to the configuration file.

1 /**/ ///Create default instance
2 Database DB = Databasefactory. createdatabase ();
3
4 /**/ ///Create a database instance
5 Database DB = Databasefactory. createdatabase ( " Northwind " );

Step 3 RunSQLStatement:

DaabCan execute staticSQLStatement, or stored procedure.

 RelatedCodeAs follows:

1 /**/ /// <Summary>
2///Returned dataset type
3/// </Summary>
4 Private Dataset getdataset ()
5 {
6 Dataset DS = DB. executedataset (commandtype. Text, " Select * from employees " );
7
8 Return DS;
9 }
10
11 /**/ ///   <Summary>
12 /// Returns the datareader type.
13 ///   </Summary>
14 ///   <Returns> </returns>
15 Private Datareader getdatareader ()
16 {
17 Datareader Dr = DB. executereader (commandtype. Text, " Select * from employees " );
18
19 Return Dr;
20 }
21
22 /**/ ///   <Summary>
23 /// Returns a single value.
24 ///   </Summary>
25 ///   <Returns> </returns>
26 Private   Int Getsiglevalue ()
27 {
28 Int Icount = DB. executescalar (commandtype. Text, " Select count (*) from employees " );
29
30 Return Icount;
31 }

Summary: This article is just a simple example.DaabIn the next advanced article, I will write and useDaabExecutes stored procedures, parameter transmission, transaction support, and connection information encryption.