Simple Login Application in Windows C#

In this post i am going to explain a simple login application in windows c# . In this App we will cover few concepts like login concept with database connection, working with multiple forms in windows c# ,  passing values from one form to another form , adding local database to our windows c# project .

For this i am designing two forms one is for Login and another is for displaying Welcome Message for logged in user .


The screenshots of application shown below .

We are designing the two forms as shown above . and we are designing a table LoginDetails in LoginDB , which is a Local Database added to our application .

Table : LoginDetails

sql query to create table :

CREATE TABLE LOGINDETAILS( NAME VARCHAR(25),PASSWORD NVARCHAR(25))

Now the C# code of Form1 is like this

using System;

using System.Windows.Forms;

using System.Data;

using System.Data.SqlClient;

namespace LoginApplication

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        string msg;

        //SqlConnection con = new SqlConnection("Data Source=LocalHost;Integrated Security=true;Initial Catalog=sameer");

       

        /** the connection string below is for connecting localdatabase LoginDB.mdf exists in the project **/

        SqlConnection con = new SqlConnection("Data Source=.\\SQLExpress;User Instance=true;Integrated Security=true;AttachDbFilename=|DataDirectory|lOGINdb.mdf");

       

        SqlCommand cmd;

        DataSet ds = new DataSet();

        private void btnlogin_Click(object sender, EventArgs e)

        {

            try

            {

                if (txtname.Text == "" || txtpassword.Text == "")

                {

                    MessageBox.Show(" Enter UserName and Password .");

                    return;

                }

                cmd = new SqlCommand("SELECT * FROM LoginDETAILS where Name='" + txtname.Text + "' and Password='" + txtpassword.Text + "'", con);

                SqlDataAdapter da = new SqlDataAdapter(cmd);

                da.Fill(ds);

                int i = ds.Tables[0].Rows.Count;

                if (i == 1)

                {

                    msg = "Welcome " + txtname.Text;

                    this.Hide();

                    Form2 f2 = new Form2(msg);

                    f2.Show();

                    ds.Clear();

                }

                else

                {

                    MessageBox.Show("Not Registered User or Invalid Name/Password");

                    txtpassword.Text = "";

                }

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

        }

        private void btnRegister_Click(object sender, EventArgs e)

        {

            try

            {

                if (txtname.Text == "" || txtpassword.Text == "")

                {

                    MessageBox.Show(" Enter UserName and Password .");

                    return;

                }

                /** checking whether name exists **/

                cmd = new SqlCommand("SELECT * FROM LoginDETAILS where Name='" + txtname.Text + "'", con);

                SqlDataAdapter da = new SqlDataAdapter(cmd);

                da.Fill(ds); //filling dataset

                int i = ds.Tables[0].Rows.Count; //checking rows count in dataset

                if (i > 0)

                {

                    MessageBox.Show("UserName "+txtname.Text+" Already Exists..");

                    txtpassword.Text = "";

                    ds.Clear(); //clearing dataset

                }

                else

                {

                    /** inserting name and password in table logindetails **/

                    cmd = new SqlCommand("INSERT INTO LOGINDETAILS VALUES('"+txtname.Text+"','"+txtpassword.Text+"')", con);

                    con.Open();

                    cmd.ExecuteNonQuery();

                    con.Close();

                   

                    msg = "Registered Successfully \n Welcome "+txtname.Text;

                    this.Hide(); //hiding form1

                    Form2 f2 = new Form2(msg);

                    f2.Show(); //showing form2

                }

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

                con.Close();

            }

        }

    }

}

and the c# code of form2 is like this

using System.Windows.Forms;

namespace LoginApplication

{

    public partial class Form2 : Form

    {

        public Form2(string msg)   //passing parameter

        {

            InitializeComponent();

            lblWelcome.Text =msg;

           

        }

   

        private void lblLogOut_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)

        {

            this.Hide();  //hiding form2

            Form1 f1 = new Form1();

            f1.Show();  //showing form1

        }

    }

Download Source Code





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