Constructing An Sql Statement Which Stops A Method.

Hi i have a page in which stock can be allocated, there are two boxes which have a product serial number start range and a product serial number end range, when these boxes are filled the "allocate" button is then clicked and the product will then be allocated the serial numbers.

What i want to happen is that when the start and end ranges have been entered into the text boxes it will fail if any number within the range has already been allocated previously. E.g



Start Range


End Range




So lets say in the start range text box 15 is entered and in the end range 25 is entered, however 18 has already been allocated previously, this will then bring up a message saying please select another range;

I have done the following so far;private void ValidateRange()

{

//String strSql;SqlConnection conn = new SqlConnection(ConfigurationManager.AppSettings["strConnectionString"]);

String strSql = "SELECT SqlCommand dbCommand4 = new SqlCommand(strSql, conn);

dbCommand4.Parameters.Add("@Start_RangeID", txt_Start_Range.Text);dbCommand4.Parameters.Add("@End_RangeID", txt_End_Range.Text);

dbCommand4.Connection = conn;

conn.Open();SqlDataReader myDataReader = dbCommand4.ExecuteReader();

myDataReader.Read();if (txt_Start_Range.Text == Convert.ToString(myDataReader["Serial_No"]))

{lblRange.Text = "Please enter a different range a portion of the selected values have already been allocated";

//Response.Redirect("Selectedfilm.aspx");

}

else

{Allocate(true);

}

 

conn.Close();

 

}

 

My problem is constructing the select statement, thanks.