From the creation of a public opinion survey to talk about object-oriented programming ideas (2)

First, we need to define a database table to save the data that the public opinion survey wants to close. See the following table:
/* News survey */
If exists (select * from sysobjects where id = object_id (Survey ))
Drop table Survey
Go

Create table Survey
(
ID int identity Primary key not null,
SurveyID varchar (20) default "" not null,
Kind tinyint default 0 not null,
Title nvarchar (100) default "" not null,
Description nvarchar (255) default "" not null,
Amount int default 0 not null,
BeginTime datetime default getdate () not null,
EndTime datetime default getdate () not null,
Active bit default 0 not null
)
Go

Well, after the database is created, I can inherit the specific subclass from the survey base class above. For example, I want to create a football match

The investigation, then we will do such a class:

Namespace Football
{
Using System;
Using MyClass. Util;
Using System. Data. SQL;
Using System. Collections;
/// <Summary>
/// Football public opinion survey
/// </Summary>
/// <Remarks>
/// Inherited from the MyClass. Util. Survey class
/// </Remarks>
Public class FootballSurvey: MyClass. Util. Survey
{

Public FootballSurvey ()
{
}

/// <Summary>
/// Overload the parent class virtual function
/// </Summary>
/// <Param name = "a_intID"> id of the database under investigation </param>
Public override void LoadFromDatabase (string a_strID)
{
MyClass. Util. MyConnection myConn = new MyConnection ();
SQLCommand myCommand = new SQLCommand ();
MyCommand. CommandText = "up_GetSurvey ";
MyCommand. CommandType = System. Data. CommandType. StoredProcedure;

Try
{
MyConn. Open ();
MyCommand. ActiveConnection = myConn;
MyCommand. Parameters. Add (new SQLParameter ("@ a_strsurveyid ",

SQLDataType. VarChar, 20 ));
MyCommand. Parameters ["@ a_strsurveyid"]. Value = a_strID;
SQLDataReader myReader;
MyCommand. Execute (out myReader );

// Take the investigation first
If (myReader. Read ())
{
This. m_strTitle = myReader ["title"]. ToString ();
This. m_intHits = (int) myReader ["amount"];
This. m_strID = a_strID;
This. m_datBeginTime =

(DateTime) myReader ["begintime"];
This. m_datEndTime = (DateTime) myReader ["endtime"];
}
Else
{
Throw (new Exception ("no record for this survey in the Database "));
}

// Clear the survey items
M_arrItems.Clear ();

// Retrieve survey items
If (myReader. HasMoreRows)
{
While (myReader. Read ())
{
SurveyItem item = new SurveyItem ();
Item. Text = myReader ["title"]. ToString ();
Item. ID = (int) myReader ["id"];
Item. Count = (int) myReader ["amount"];
Item. Description =

MyReader ["Description"]. ToString ();
AddItem (item );
}
}
Else
{
Throw (new Exception ("the database does not have any items related to this survey.

"));
}

// Clear the scene
MyReader. Close ();
MyConn. Close ();
}
Catch (Exception e)
{
Throw (new Exception ("failed to read from database:" +

E. ToString ()));
}
}

/// <Summary>
/// Save the survey to the database
/// </Summary>
/// <Param name = "m_strSurveyID"> Survey No. </param>
/// <Remarks>
/// If m_strSurveyID is not empty, delete the original record and use the current investigation number to save the new investigation,
/// Otherwise, a new survey number is generated.
/// </Remarks>
Public override void SaveToDatabase (string m_strSurveyID)
{
// If there is no title or investigation item, an exception is thrown.
If (this. m_arrItems.Count = 0 | this. m_strTitle = "")
{
Throw (new Exception ("no survey title or title item "));
}

MyClass. Util. MyConnection myConn = new MyConnection ();
SQLCommand myCommand = new SQLCommand ();
MyCommand. CommandType = System. Data. CommandType. Text;

Try
{
MyConn. Open ();
MyCommand. ActiveConnection = myConn;

// Generate a surveyid if no surveyid exists
String strSurveyID;
If (m_strSurveyID = "")
{
StrSurveyID = DateTime. Now. Year. ToString ()
+

DateTime. Now. Month. ToString ()
+

DateTime. Now. Hour. ToString ()
+

DateTime. Now. Minute. ToString ()
+

DateTime. Now. Second. ToString ()
+

DateTime. Now. Millisecond. ToString ();
}
Else // Delete this record if it already exists
{
StrSurveyID = m_strSurveyID;
// Delete the original record
MyCommand. CommandText = "delete from survey where

Surveyid = "+ strSurveyID + "";
MyCommand. ExecuteNonQuery ();
}

String strSql = "insert into survey (surveyid, kind, title)

Values ("
+ StrSurveyID + ", 0," +

M_strTitle + ")";
For (int I = 0; I <m_arrItems.Count; I ++)
{
StrSql + = "insert into survey (surveyid, kind,

Title) values ("
+ StrSurveyID + ", 1 ,"
+ (SurveyItem) m_arrItems [I]). Text +

")";
}
// Insert a database
MyCommand. CommandText = strSql;
MyCommand. ExecuteNonQuery ();

// Clear the scene
MyConn. Close ();
}
Catch (Exception e)
{
Throw (new Exception ("error saving investigation:" + e. ToString ()));
}

}

/// <Summary>
/// Vote
/// </Summary>
/// <Param name = "a_intID"> </param>
Public override void Vote (int a_intID)
{
// Add one to the count
(SurveyItem) m_arrItems [a_intID]). Count + = 1;

// Changes in the database
MyConnection myConn = new MyConnection ();
SQLCommand myCommand = new SQLCommand ();
MyCommand. CommandText = "update survey set amount = amount + 1 where

Id ="
+

(SurveyItem) m_arrItems [a_intID]). ID. ToString ();

MyCommand. CommandType = System. Data. CommandType. Text;

Try
{
MyConn. Open ();
MyCommand. ActiveConnection = myConn;
MyCommand. ExecuteNonQuery ();
MyConn. Close ();
}
Catch (Exception e)
{
Throw (new Exception ("failed to update the survey item:" + e. ToString ()));
}

}

/// <Summary>
/// Survey list
/// </Summary>
Public static ArrayList SurveyList ()
{
ArrayList arrResult = new ArrayList ();
MyClass. Util. MyConnection myConn = new MyConnection ();
SQLCommand myCommand = new SQLCommand ();
MyCommand. CommandText = "select id, surveyid, title from survey

Where kind = 0 order by surveyid desc ";
MyCommand. CommandType = System. Data. CommandType. Text;

Try
{
MyConn. Open ();
MyCommand. ActiveConnection = myConn;
SQLDataReader myReader;
MyCommand. Execute (out myReader );
While (myReader. Read ())
{
FootballSurvey mySurvey = new FootballSurvey ();
MySurvey. Title = myReader ["title"]. ToString ();
MySurvey. SurveyID = myReader ["surveyid"]. ToString ()

;
ArrResult. Add (mySurvey );
}

MyReader. Close ();
MyConn. Close ();

}
Catch (Exception e)
{
Throw (new Exception ("Retrieving from database failed:" +

E. ToString ()));
}

// Return results
Return arrResult;
}

/// <Summary>
/// Obtain the active survey id
/// </Summary>
Public static string GetActiveSurveyID ()
{
String strResult = "";

MyClass. Util. MyConnection myConn = new MyConnection ();
SQLCommand myCommand = new SQLCommand ();
MyCommand. CommandText = "select top 1 id, surveyid from survey

Where active = 1 order by id desc ";
MyCommand. CommandType = System. Data. CommandType. Text;

Try
{
MyConn. Open ();
MyCommand. ActiveConnection = myConn;
SQLDataReader myReader;
MyCommand. Execute (out myReader );
If (myReader. Read ())
{
StrResult = myReader ["surveyid"]. ToString ();
}
Else
{
Throw (new Exception ("inactive investigation "));
}

MyReader. Close ();

}
Catch (Exception e)
{
Throw (new Exception ("Retrieving from database failed:" +

E. ToString ()));
}
Finally
{
MyConn. Close ();
}

// Return results
Return strResult;

}

/// <Summary>
/// Activate the survey
/// </Summary>
/// <Param name = "a_strSurveyID"> Survey No. </param>
Public static void ActiveSurvey (string a_strSurveyID)
{
MyClass. Util. MyConnection myCo