如何在从数据库收集数据时通过登录页面在C＃中打开不同的表单页面

Question

I'm making a Grocery store application that connects with a database. I've 3 users at login page Manager Cashier1 and Cashier 2. I want to open form of the relevant user as data is already saved in the database. like when I enter Manager and password of manager it should access Manager pager. when i Enter Cashier credentials it should open Cashier page my code is below thank you.

I'm using C# windows form application.

If it is possible to extract only password field from the database and then compare it with txtUser.text will it work that way or not?

    private void btnLogin_Click(object sender, EventArgs e)
    {
        SqlConnection con1 = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Northwind;Integrated Security=True");
        string query= "select * from ManCash Where USERNAME='"+txtUser.Text+"'and PASS = '"+txtPass.Text+"'";

        SqlDataAdapter sda = new SqlDataAdapter(query, con1);
        DataTable DT = new DataTable();
        sda.Fill(DT);

        if (DT.Rows.Count>0&&DT.Rows.Count<=1)
            {
                this.Hide();
                Manager frm4 = new Manager();
                frm4.ShowDialog();
                this.Close();
            }
        else if(DT.Rows.Count>1&&DT.Rows.Count<=2)
            {
                this.Hide();
                Cashier frm5 = new Cashier();
                frm5.ShowDialog();  
                this.Close();
            }
         else if (DT.Rows.Count==3)
            {
                 this.Hide();   
                 Cashier frm5 = new Cashier();
                 frm5.ShowDialog();
                 this.Close();
            }

Answer 1

You will want to use SQLCOMMAND AND SQLDATAREADER to read the return value of Select statement then put it in a switch statement and make a role for each user. SO that when you login it will automatically match that user on its specific role and open up the exact form.

Answer 2

Since I don't know how to code in C#, I would like to give you a advice here.

1) Create a new column in your ManCash table and name it 'Role'

2) In your Role column, you may make it as a varchar or int If you made it as varchar put admin if it is for the manager, put staff if not. And if int put 1 for manager and 0 for staff.

3) Create a query similar to the following:

(written in pseudo code)

if datatable returns 1 from "Select role from ManCash where username = @username and password = @password" then proceed to next statement

4) Retrieve the value from the roles table, that way, you may segregate the pages to be shown like this pseudo code

if query returned manager then manager page else staff page

5) I suggest you read the basics of Database management, as a developer, you may want to learn how to manage a database, with this knowledge, you'll learn how to make applications faster, more efficient, and secure.

Answer 3

private void btnLogin_Click(object sender, EventArgs e)
{
    SqlConnection con1 = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Northwind;Integrated Security=True");
    string query= "select * from ManCash Where USERNAME='"+txtUser.Text+"'and PASS = '"+txtPass.Text+"'";
SqlCommand cmd=new SqlCommand();
cmd.CommandText="query";
cmd.Connection=con1;
con1.Open();
SqlDataReader reader=cmd.ExecuteReader();
Switch(reader["Role"].toString()){
case "Manager":
//redirect to role form
break;
case "Cashier1":
//redirect to role form
break;
case "Cashier2":
//redirect to role form
break;
default:
break;
}
con1.Close();

if there's an error , try to fix it with your own i'm just giving the Exact logic to get it done :)

Answer 4

It has worked like this without any error. But thank you all to respond so quickly.

    SqlConnection con1 = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Northwind;Integrated Security=True");

    private void btnLogin_Click(object sender, EventArgs e)
    {
        string query= "select * from ManCash Where USERNAME='"+txtUser.Text+"'and PASS = '"+txtPass.Text+"'";
        SqlDataAdapter sda = new SqlDataAdapter(query, con1);

        DataTable DT = new DataTable();
        //  SqlCommand command = new SqlCommand("SELECT Role from ManCash Where USERNAME='" + txtUser.Text + "'and PASS = '" + txtPass.Text + "'", con1);
        // SqlDataReader readr = command.ExecuteReader();
        sda.Fill(DT);

        string a = DT.Rows[0]["Role"].ToString();

        switch (a)
        {
            case "Admin":
                this.Hide();
                Manager man = new Manager();
                man.ShowDialog();
                this.Close();
                break;
            case "Staff":
                this.Hide();
                Cashier ca = new Cashier();
                ca.ShowDialog();
                this.Close();
                break;
        }
    }