How to count the number of online users and the number of historical visitors

Preparations
1. Create a database for Tongji and add a table for Tongji. There is a number field in the table, which is of the int type. The initial value of number is 1000;
2. Create a website;
3. Create a database connection string (specific method) and save it to the Web. config file. The code in the <connectionstrings> section is as follows:

<Connectionstrings>
<Add name = "tongjiconnectionstring" connectionstring = "Data Source =.; initial catalog = Tongji; Integrated Security = true" providername = "system. Data. sqlclient"/>
</Connectionstrings>

Key code
4. Add a new project/global application class: Global. asax. The code for the file is as follows:

<% @ Application language = "C #" %>
<% @ Import namespace = "system. Data. sqlclient" %>

<SCRIPT runat = "server">

Void application_start (Object sender, eventargs E)
{
// Code that runs when the application starts
Sqlconnection con = new sqlconnection ();
Con. connectionstring = configurationmanager. connectionstrings ["tongjiconnectionstring"]. connectionstring;
Con. open ();
Sqlcommand cmd = new sqlcommand ("select * from Tongji", con );
Int COUNT = convert. toint32 (CMD. executescalar ());
Con. Close ();
Application ["Total"] = count;
Application ["online"] = 0;
}

Void application_end (Object sender, eventargs E)
{
// Code that runs when the application is closed
Sqlconnection con = new sqlconnection ();
Con. connectionstring = configurationmanager. connectionstrings ["tongjiconnectionstring"]. connectionstring;
Con. open ();
Sqlcommand cmd = new sqlcommand ("Update Tongji set number =" + application ["Total"]. tostring (), con );
Cmd. executenonquery ();
Con. Close ();
}

Void application_error (Object sender, eventargs E)
{
// Code that runs when an unhandled error occurs
}

Void session_start (Object sender, eventargs E)
{
// The code that runs when the new session starts
Application. Lock ();
Application ["Total"] = (INT) application ["Total"] + 1;
Application ["online"] = (INT) application ["online"] + 1;
Application. Unlock ();
}

Void session_end (Object sender, eventargs E)
{
// The code that runs when the session ends.
Application. Lock ();
Application ["online"] = (INT) application ["online"]-1;
Application. Unlock ();
}

</SCRIPT>

Run the test
5. Drag two labels to default. aspx;
6. Its default. aspx. CS code is as follows:

Public partial class _ default: system. Web. UI. Page
{
Protected void page_load (Object sender, eventargs E)
{
This. label1.text = "Total Number of visitors" + application ["Total"]. tostring ();
This. label2.text = "Current online quantity" + application ["online"]. tostring ();
}
}

7. OK !! Start debugging.

Notes

8. When debugging in vs2005, the total number of visitors is 1001. Currently, the number of online users is 1;
I re-open another IE and copy the address to it. The total number of visitors is 1002, and the current number of online users is 2;
This means everything is normal. But it is still 1000 in the database ,??????
I am here to delay a lot of time (one day), but in my despair, I tried again,
This time, however, God gave me an unexpected gift.

In vs2005, select "save global" from the "file" menu ";
In this case, the value 1000 in the database is updated to 1002.
If the same is true for I s debugging, you must shut down or stop the WWW Service before writing data into the database.

Knowledge Summary

· Database connection and use of related objects
· Application object usage
· Use of session objects