Code for new user related issues

Question

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Hi,
Am doing ma final year project on asp.net-c# which is a website for a hospital.
I've 3 questions.
1)When an user has created an account already and tries to create another account with the same name an error msg should be displayed. I've given username as primary key.

using System;
public partial class appointment : System.Web.UI.Page
{
    public SqlConnection con = new SqlConnection("Data Source=ADMINISTRATOR\\SQLEXPRESS;Initial Catalog=Hospital;Integrated Security=True");
    public SqlDataAdapter da;
    public DataSet ds;
    protected void Page_Load(object sender, EventArgs e)
    {
        lblexists.Visible = false; // label box to display an error msg
    }
    protected void btnaccount_Click(object sender, EventArgs e)
    {
        con.Open();
        { 
            SqlCommand cmd = new SqlCommand("insert into Userreg values('" + txtnewuser.Text + "','" + txtnpwd.Text + "','" + txtcpwd.Text + "','" + txtphone.Text + "','" + txtemail.Text + "','" + txtlocation.Text + "')", con);                  
            cmd.ExecuteNonQuery();           
            Page.ClientScript.RegisterStartupScript(this.GetType(), "me", "alert('Account Created succecfully')", true);            
            txtnewuser.Text = "";           
            txtnpwd.Text = "";            
            txtcpwd.Text = "";            
            txtphone.Text = "";            
            txtemail.Text = "";
            txtlocation.Text = "";
         con.Close();
        }
        Response.Redirect("reqopat.aspx");
    }
}

2)I've used a webpage where users can request an appointment. I've used 2 ddl, ddl ID=SelectASpeciality for department names and ddl ID=SelectADoctor for doctor names. When I select a department name from SelectASpeciality ddl, I wan all the doctors of that department to be displayed in SelectADoctor ddl.

3)I've created a XML file for AdRotator. But am not able add image url. How do I add image url.

Plz help me with an easy code so that i can answer ma viva questions with ease.

Posted 3-Mar-12 4:11am

Nisha1705

Updated 3-Mar-12 4:18am

Not Active

v3

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[no name] 3-Mar-12 10:18am

Format code snippets and only include what is necessary. The using statments were not necessary

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Not Active · Accepted Answer · 2012-03-03T04:26:00

First of all, NEVER accept unvalidated user input and concatenate a SQL command. EVER! Got it?!? Do some research on SQL Injection attack.

Don't instantiate your connection object globally. Create it only when necessary.

Learn to about using clause, as in

using(SqlCommand cmd = new SqlCommand(...))
{

}

There is already a user database available with all the functionality for registration, unique naming, password reset, etc. http://msdn.microsoft.com/en-us/library/ms229862(v=vs.80).aspx[^]

Dave Kreskowiak · Accepted Answer · 2012-03-03T06:39:00

Solution 3

I'm kind of surprised nobody mentioned this, but a "username" is a LOUSY primary key. DO NOT DO THAT!

Let the database autoassign ID numbers as the primary key for your user table.

Posted 3-Mar-12 6:39am

Dave Kreskowiak

Comments

Sergey Alexandrovich Kryukov 3-Mar-12 18:31pm

Good point, a 5.
--SA

Dave Kreskowiak 3-Mar-12 18:33pm

You add another column to the table, usually called Id or UserId. Since your project isn't very big and isnt likely to see world wide production, the column type would be an Integer. You set this column as Auto Increment anf Primary Key.

Why is it bas to use user names as the key? Because users are usully able to change their userId.

Nisha1705 4-Mar-12 9:27am

I got ur point.. Thanku so much i'll implement what u said.

Sergey Alexandrovich Kryukov · Accepted Answer · 2012-03-03T12:32:00

Solution 4

Please see:
http://en.wikipedia.org/wiki/SQL_injection[^].

(In addition to the important point made by Mark Nischalke.)

—SA

Posted 3-Mar-12 12:32pm

Sergey Alexandrovich Kryukov

Comments

Nisha1705 4-Mar-12 9:31am

Thanks for ur link. Now i've got an idea of how to go ahead.

Sergey Alexandrovich Kryukov 4-Mar-12 12:00pm

You are welcome.
If so, will you accept this answer formally, too? You can accept more than one.
--SA

Yogesh Sonar · Accepted Answer · 2012-03-03T04:18:00

Solution 1

1) Firstly u check whether there is record or not with the username which is being inserting. If not exist in table, then insert the record. Otherwise you display the proper error message.

Posted 3-Mar-12 4:18am

Yogesh Sonar

Comments

Nisha1705 3-Mar-12 12:24pm

There is a record of the account created in the table. What i want is when a user tries to create an account with the same name an error msg shud display. When i execute the code mentioned above it says violation of primary key. I don wan t't to happen. Instead i wan an error msg to be displayed.
Since am a beginner i don understand much abt .net... So plz help me to solve dis..

[no name] 3-Mar-12 12:51pm

A generic reply that give no useful information to the OP

Code for new user related issues

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