Schema mode for. Net

One: three-tier architecture implemented by ADO

Do not use the three-layer common query notation:

String sql = string. Format ("select * from studnet where stuname like '%{0}% '", txtname.text);            String strconn = "server=.; database=mysc;uid=sa;pwd=123456 ";            SqlConnection conn = new SqlConnection (strconn);            SqlDataAdapter da = new SqlDataAdapter ("select * Fromstuden", conn);            DataSet ds = new DataSet ();            Try            {                da. Fill (DS);               Datagridview1.datasource = ds. Tables[0];                DataTable dt = ds. Tables[0];                txtName.Text = dt. rows[0]["Name"]. ToString ();            }            catch (Exception)            {                throw;            }

Common deletion:

  SqlConnection conn = new SqlConnection ("server=.; database=mysc;uid=sa;pwd=123456 ");            String id = datagridview1.selectedrows[0]. Cells[0]. Value.tostring ();            String sql = "Delect from Student where stno=" + ID;            SqlCommand comm = new SqlCommand (sql,conn);            Conn. Open ();

General wording of the modification:

   String strSQL = @ "UPDATE Student SET [stuname]= ' 0 ' WHERE [stuno]={3}";            String id = datagridview1.selectedrows[0]. Cells[0]. Value.tostring ();            String sql = string. Format (strSQL, txtname.text, id);            SqlConnection conn = new SqlConnection ("server=.; database=mysc;uid=sa;pwd=123456 ");            SqlCommand com = new SqlCommand (SQL, conn);            Try            {                Conn. Open ();                Com. ExecuteNonQuery ();                Refresh Data            }            catch (Exception)            {                throw;            }            finally {                Conn. Close ();            }

A simple dbhelper:

 Private StaticSqlConnection conn =NewSqlConnection ("server=.; database=mys,uid=sa;pwd=123456");  Public Static intExecuteSQL (stringstrSQL) {SqlCommand Comm=NewSqlCommand (strSQL, conn); Try{Conn.               Open (); returnComm.           ExecuteNonQuery (); }           Catch(Exception ex) {Throwex; }           finally{Conn.           Close (); }       }        Public Static intGetdatatable (stringstrSQL) {SqlDataAdapter da=NewSqlDataAdapter (strSQL, Conn); DataSet DS=NewDataSet (); Try{da.               Fill (DS); returnDs. tables[0]; }           Catch(Exception ex) {Throwex; }                           }       /// <summary>       ///returns a single value/// </summary>       /// <param name= "strSQL" >The incoming SQL statement (select COUNT (*), select Max (. ))</param>       /// <returns>The object type is returned</returns>        Public Static ObjectGetsingle (stringstrSQL) {SqlCommand Comm=NewSqlCommand (strSQL, conn); Try{Conn.               Open; returnComm.           ExecuteScalar (); }           Catch(Exception ex) {Throwex; }           finally{Conn.           Close (); }       }

Second: three-tier architecture with OOP

Three: The application of abstract Factory + reflection to achieve a common data source design

Schema mode for. Net