Insert values in table from front-end CategoryId
On Button Click, I got to do something like this, as suggested by @MarkSinkinson.

protected void btnSubmit_Click(object sender, EventArgs e)
{
    SqlCommand cmd = new SqlCommand("Insert into CategoriesForMerchant (CategoryName) values (@CategoryName)", conn);
    cmd.Parameters.AddWithValue("@CategoryName", txtCategory.Text);
    conn.Open();
    cmd.ExecuteNonQuery();
    conn.Close();
    Response.Write("&lt;script&gt;alert('File uploaded successfully');&lt;/script&gt;");
}