vb.net - I m trying to fetch total in to TextBox5.text but error occured -

i m trying fetch total in textbox5.text error occured no value given 1 or more required parameters.

try con.close()

        con.connectionstring = "provider=microsoft.jet.oledb.4.0;data source=pradnya_datab.mdb"          con.open()          ss = "select total stock_bottle bottle_type=" & convert.tostring(textbox3.text.tostring())          cmd = new oledbcommand(ss, con)          rd = cmd.executereader()          if rd.read()              textbox5.text = rd("total").tostring()          end if          con.close()         rd.close()       catch ex exception         msgbox(ex.message)     end try 

this error occurs when 1 or more of column names , table name not spelled correctly. in case, means total or bottle_type or stock_bottle not correct name fields or table.

saying that, , pending due correction query, suggest use more robust code one

try     dim ss = "select total stock_bottle bottle_type=@btype"     using con = new oledbconnection("provider=microsoft.jet.oledb.4.0;data source=pradnya_datab.mdb")     using cmd = new oledbcommand(ss, con)         con.open()         cmd.parameters.add("@btype", oledbtype.int32).value = textbox3.text         dim result = cmd.executescalar()         if result isnot nothing             textbox5.text = result.tostring()         end if     end using     end using catch ex exception     msgbox(ex.message) end try 

here have changed query parameterized query. it more safe , robust correct interpretation of datatype used clause. have removed global variable connection. (you don't advantage , need check status of connection).
have added using statement ensure proper closing of connection , immediate release of system resources kept connection.

finally, if need retrieve 1 row 1 single column not use more expensive oledbdatareader (useful when there many rows , columns read back) directly oledbcommand executescalar method