The encapsulation of data access classes and the three main classes

Encapsulation of data access classes:

Data access classes fall into three main categories: Connection classes, entity classes, and data access classes.

1. Connection class:

public class Lianjie

{private static string connection= ' server=.; database=mydb;uid=sa;pwd=789234178 ";

public static Sqlconnection Conn

{Get

{

SqlConnection conn=new SqlConnection (connecction);

Return conn; }

}

}

2, Entity class: private string Code; To encapsulate a property

3. Data Access class:

public class table Name da

{

Private SqlConnection Conn; Private Sqlcommand cmd;

Private SqlDataReader Dr;

Public Teseda ()

{

Conn=lianjie.conn; Cmd=conn. CreateCommand ();

}

Public list< table name >selectall () query table all

{

cmd.commandtext= "Select*from table name";

Conn. Open ();

Dr=cmd. ExecuteReader ();

List<test>list=new list<test> ();

while (Dr. Read ())

{

Test data=new test ();

Data. code=dr["Code"]. ToString ();

Data. name=dr["Name"]. ToString ();

Data. pwd=dr["PWD"]. ToString ();

List. ADD (data);

}

Conn. Close (); return list;

}  }

The encapsulation of data access classes and the three main classes