how to check user already exist in th database or not

Question

I have a form i just want to check whether that user in already exist or not and if not then it save in the database else show error message user already exist in know this question i asked many times but i didnt find my solution here is my aspx code:

protected void btnSubmit_Click(object sender, EventArgs e)
{
    con.Open();
    string FirstName = tbFirstName.Text;
    string LastName = tbLastName.Text;
    string Email = tbEmail.Text;
    string Pass = tbPass.Text;
    string ConfirmPass = tbConfirmPass.Text;
    using (SqlCommand cmd = con.CreateCommand())
    {
       cmd.CommandText = "Insert into UserDetails(@FirstName,@LastName,@Email,@Pass,@ConfirmPass)values('" + tbFirstName.Text + "','" + tbLastName.Text + "','" + tbEmail.Text + "','" + tbPass.Text + "','" + tbConfirmPass.Text + "')";
       cmd.Parameters.AddWithValue("@FirstName", tbFirstName.Text.Trim());
       cmd.Parameters.AddWithValue("@LastName", tbLastName.Text.Trim());
       cmd.Parameters.AddWithValue("@Email", tbEmail.Text.Trim());
       cmd.Parameters.AddWithValue("@Pass", tbPass.Text.Trim());
       cmd.Parameters.AddWithValue("@ConfirmPass", tbConfirmPass.Text.Trim());
    }
    con.Close();
    tbFirstName.Text = "";
    tbLastName.Text = "";
    tbEmail.Text = "";
    tbPass.Text = "";
    tbConfirmPass.Text = "";
    tbFirstName.Focus();
    }

in this on click event of button user can only be created but i want to verify whether it is present in the database or not

This search has 697 results - they're not all relevant but I'm sure many on this first page are. http://stackoverflow.com/search?q=insert+already+exists+sql-server — Aaron Bertrand, Apr 29 '13 at 14:51

score 1 · Accepted Answer · answered Apr 29 '13 at 15:21

Try this code, It may help you. call this function on your click event.

public void CheckUser()
 {

    string strconn = @"Data Source=appserver3;Initial Catalog=Bart;User ID=bart1;Password=bart@12345";
    SqlDataReader reader = null;

    SqlConnection conn = null;

    conn = new SqlConnection(strconn);
    conn.Open();

    DateTime Dt_Time = DateTime.Now;
    string FirstName = tbFirstName.Text;
    SqlCommand cmd = new SqlCommand("select FirstName from UserDetails where @FirstName='" + tbFirstName.Text + "'", conn);
    cmd.Parameters.AddWithValue("@FirstName", tbFirstName.Text.Trim());
    reader = cmd.ExecuteReader();
    if (reader != null && reader.HasRows)
    {
        Response.Write("<script>alert('User Already Exist');</script>");
    }
    else
    {
        string strquery = string.Format("insert into UserDetails values('{0}')", @FirstName);
        cmd = new SqlCommand(strquery, conn);
        int count = (int)cmd.ExecuteNonQuery();
        Response.Write("FirstName:" + FirstName);               
    }
}

how to check user already exist in th database or not

1 Answers1