First of all we have to design a table in database in order to store the user and password of the entire user who can log on to our application having at least two entities ‘username’ and ‘password’ , here my database name is ‘Employee’ and table name is ‘login’.

Our next step is to design login form.

 

Set the password text box ‘password char’ to ‘*’.

Now, once the login form and tables are designed our next step is to design the code for the login form.

Coding

        Boolean log = false;
 
//Assigning public variable log of type Boolean to set property of this from
//in order to access it from  other form.
 
        public Login()
        {
            InitializeComponent();
        }
       
        private void btnCancel_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
 
//Application will exit if cancel button is clicked.
 
        public void fnlogin()
        {
 
//Function for login
 
            try
            {
 
//Managing connection to the database
 
                string sqlString = "Server=abc\\SQLEXPRESs;Database=Employee;Trusted_Connection=True";
                SqlConnection con = new SqlConnection(sqlString);
                con.Open();
                SqlCommand cmd = new SqlCommand("select UserName, Password from login whereUserName='" + txtUserName.Text.Trim() + "' and Password='" + txtPassword.Text.Trim() + "'", con);
 
//Fetching only those records from the table which matches with the record
//in the text field in the login form.
                SqlDataReader rdr = cmd.ExecuteReader();
                if (rdr.HasRows)
                {
 
//checking whether datareader contains any rows or not. If the condition
//is true then the code below will be executed otherwise code in else
//block will be executed.
 
                    while (rdr.Read())
                    {  
//Reading all records fetched, one by one and matching with the user name
//and password entered by user, in order to overcome small and upper caps
//complexities in user name and password.
                        if (rdr[0].ToString().ToUpper() ==txtUserName.Text.Trim().ToUpper() && txtPassword.Text==rdr[1].ToString())
                        {
                            log= true;
                            this.Close();
                        }
                        else
                        {
//If username or password provider by the user are incorrect then
//following message will be displayed.
                            MessageBox.Show("User Name or Password incorrect!!!");
                            txtUserName.Text= "";
                            txtPassword.Text= "";
                            txtUserName.Focus();
                            log= false;
                        }
                    }
                                 
                }
                else
                {
                    MessageBox.Show("User Name or Password incorrect!!!");
                    txtUserName.Text = "";
                    txtPassword.Text = "";
                    txtUserName.Focus();
                    log = false;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        private void btnLogin_Click(object sender, EventArgs e)
        {
            fnlogin();           
        }
 
        private void txt_KeyPress(object sender, KeyPressEventArgs e)
        {
//Checking whether enter key is pressed in text boxes or not.
            if (e.KeyChar == (char)13)
                fnlogin();
        }
 
//Setting property of this form in order to use it in another form
//so as to get the information whether the login was successful or not.
        public Boolean pLog
        {
            get
            {
                return log;
            }
            set
            {
                log = value;
            }
        }

Screen Shot

 

Message displayed if username and password provider are incorrect.