Duplicate Email address Validation on registration page if Email address already registered using C# in ASP.Net

Hi yati,

can you tell what your select query is returning  as per your query it is returning "ap_username" so is it mail id column where you are saving the mail id's of the users or it is different one.

Below is the updated code. ap_emailh is the hidden field that hold email input. The input for ap_username is email but now i was currently change the code but still not working :(

else if (txtEmail.Text.Trim() != "")
{
    string apemail = txtEmail.Text;
    String email = ap_emailh.Value;

    if (ap_emailh.Value != email)

    {
        // check duplicate email ID

        String queryB = "SELECT ap_email FROM tbl_applicantsdetails WHERE ap_email = '" + apemail + "' OR ap_email <> '" + email + "' ";

        SqlCommand cmdB = new SqlCommand(queryB, con);
        SqlDataReader drB = cmdB.ExecuteReader();

        if (drB.Read())
        {

            // Message("Duplicate email found.");
            cvApplicantUpdate.ErrorMessage = "Email address already exists";
            txtEmail.Focus();
            e.IsValid = false;

            drB.Close();
        }
    }
}

Hi yati,

 I have some modified in your code. So please refer the code below.

C#

else if (txtEmail.Text.Trim() != "")
    {
        string apemail = txtEmail.Text;
        String email = ap_emailh.Value;
            // check duplicate email ID
 
            String queryB = "SELECT ap_email FROM tbl_applicantsdetails WHERE ap_email = '" + apemail + "' OR ap_email='" + email + "' ";
                SqlCommand cmdB = new SqlCommand(queryB, con);
            SqlDataReader drB = cmdB.ExecuteReader();
 
            if (drB.HasRows)
            {
                // Message("Duplicate email found.");
                cvApplicantUpdate.ErrorMessage = "Email address already exists";
                txtEmail.Focus();
                e.IsValid = false;
 
                drB.Close();
            }
}

I hope works for you.

hi Indresh,

Thank you .I appreciate your help. Already try but still not working.

Hi yati,

I have created sample code which full-fill your requirement.

HTML

<div>
    Email Id:
    <asp:TextBox ID="txtEmailAddress" OnTextChanged="onEmailCheck" AutoPostBack="true"
        runat="server" />
    <asp:Label ID="lblMessage" ForeColor="Red" Text="" runat="server" />
</div>

C#

protected void onEmailCheck(object sender, EventArgs e)
{
    SqlConnection con = new SqlConnection(constring);
    string EmaiId = txtEmailAddress.Text.Trim();

    SqlCommand cmd = new SqlCommand("SELECT EmailAddress FROM tblEmployee WHERE EmailAddress ='" + EmaiId + "'", con);
    con.Open();
    SqlDataReader idr = cmd.ExecuteReader();
    if (idr.HasRows)
    {
        lblMessage.Text = "Email address already exists";
        txtEmailAddress.Focus();
    }
    else
    {
        lblMessage.Text = "";
    }
    con.Close();
}

Screenshot