How to call the class file method to windows form in C# windows application.

Question

1.00/5 (1 vote)

See more:

I'm fresher this is my first project.I have Written this method in windows form directly.Now i Want to implement 2-tier architecture.
I will post the code.Actual method in windows project.And What code i have written in class file both.
Now if i create method like that how to bind to the combobox.Please Help me how to do this.

What I have tried:

C#

this code i was written in windows project
----------------------------------------------

       private void FillBankName()
        {
            SqlConnection con = new SqlConnection(connectionString);
            con.Open();
            SqlCommand cmd = new SqlCommand("select bank_Id,bank_Name from 
   bankdetails", con);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            Dictionary Dctbnk = new Dictionary();
            Dctbnk.Add("select", "select");
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                Dctbnk.Add(dt.Rows[i]["bank_Name"].ToString(), dt.Rows[i]["bank_Id"].ToString());
            }
            cmbBankname.ValueMember = "Value";
            cmbBankname.DisplayMember = "Key";
            cmbBankname.DataSource = new BindingSource(Dctbnk, null);
            con.Close();
--thisis i written inclass  file
--------------------------------------------
          public DataTable FillBankName()
        {
            SqlConnection con = new SqlConnection(connectionString);
            con.Open();
            SqlCommand cmd = new SqlCommand("select bank_Id,bank_Name from bankdetails", con);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            Dictionary<string, string> Dctbnk = new Dictionary<string, string>();
            Dctbnk.Add("select", "select");
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                Dctbnk.Add(dt.Rows[i]["bank_Name"].ToString(), dt.Rows[i]["bank_Id"].ToString());
            }    
            con.Close();
            return dt;
}

Posted 6-Jun-17 1:57am

Member 13153537

Updated 6-Jun-17 2:27am

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2017-06-06T02:27:00

Um. There's a lot of odd code there.
Look at your FillBankName method: why are you doing anything with the dictionary Dctbank, when you don't use it for anything afterwards, and throw it away when the method ends?

I'd suggest that you step back and think about what you want to use to pass data around: Dictionary or DataTable, and write functions which return the appropriate type.
I'd also suggest that you start using Dispose for SQL components: they are scarce resources and should be enclosed in a using block. So the DataTable version would be:

C#

public DataTable FillBankName()
    {
    DataTable dt = new DataTable();
    using (SqlConnection con = new SqlConnection(connectionString))
        {
        con.Open();
        using (SqlCommand cmd = new SqlCommand("SELECT bank_Id,bank_Name FROM bankdetails", con))
            {
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
                {
                sda.Fill(dt);
                }
            }
        }
    return dt;
    }

Multi-tier organisation is about separation of concerns: the DB tier knows about the DB only, and the presentation tier knows how to interface with the user and translate that into stuff the data tier can understand. Adding what is effectively presentation code into your data code (such as your "select", "select" row) isn't a good idea, as it forced the data layer to "know" what is happening. I'd stick with DataTable (or better, a collection of a defined class specific to the data you transfer) instead of going with the Dictionary as part of the interface.