Package of SqlHelper

Add a custom SqlHelper class to your project that simplifies the code to connect to the database:

respectively:

ExecuteNonQuery ();

ExecuteScalar ();

Executedatatables ();

There are three versions: the third version is better than the other.

Using system;using system.collections.generic;using system.linq;using system.text;using System.Configuration;using System.data.sqlclient;using System.data;namespace adonet2{class SqlHelper {private static string connstr = configurationmanager.connectionstrings["Dbconnstr"].        ConnectionString; The principle of encapsulation method: Put the invariable into the method, put the change in the parameter//First Edition disadvantage: cannot use parameter insertion        public static int ExecuteNonQuery (String sql)//{//using (SqlConnection conn = new SqlConnect Ion (CONNSTR))//{//Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL; return CMD.        ExecuteNonQuery (); }//}//}//public Static Object ExecuteScalar (String sql)//{//Usin G (SqlConnection conn = new SqlConnection (CONNSTR))//{//Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL; return CMD.        ExecuteScalar ();  }//}//}////is used only to execute query results less than SQL//public static DataTable executedatatable (string  SQL)//{//using (SqlConnection conn = new SqlConnection (CONNSTR))///{//      Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL;        SqlDataAdapter adapter = new SqlDataAdapter (cmd);        DataSet DataSet = new DataSet (); Adapter.        Fill (DataSet); return DataSet.        Tables[0];        //        }        //    }        ////}//second Edition, you can use parameters, but trouble          public static int ExecuteNonQuery (string sql,sqlparameter[] parameters)//{//using (Sqlconnec tion conn = new SqlConnection (CONNSTR))//{//Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL; foreach (SqlParameter param in Parameters)////{////CMD.        Parameters.Add (param); }//cmd.        Parameters.addrange (Parameters); return CMD.        ExecuteNonQuery ();        }//}//}//public Static Object ExecuteScalar (string sql,sqlparameter[] parameters) {//using (SqlConnection conn = new SqlConnection (CONNSTR))//{//Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL; //           Cmd.        Parameters.addrange (Parameters); return CMD.        ExecuteScalar ();  }//}//}////is used only to execute query results less than SQL//public static DataTable executedatatable (string     SQL, sqlparameter[] parameters)//{//using (SqlConnection conn = new SqlConnection (CONNSTR))// {//Conn.        Open (); using (SqlCommand cmd = conn.        CreateCommand ())//{//cmd.commandtext = SQL; Cmd.        Parameters.addrange (Parameters);        SqlDataAdapter adapter = new SqlDataAdapter (cmd);        DataSet DataSet = new DataSet (); Adapter.        Fill (DataSet); return DataSet.        Tables[0];       //        }        //    }        //}//Third Edition: Use length variable parameters to simplify          public static int ExecuteNonQuery (string sql,params sqlparameter[] parameters) {using (Sqlconne Ction conn = new SqlConnection (CONNSTR)) {Conn.                Open (); using (SqlCommand cmd = conn.                    CreateCommand ()) {cmd.commandtext = SQL; foreach (SqlParameter param in Parameters)//{//cmd.                    Parameters.Add (param); } cmd.                    Parameters.addrange (Parameters); return CMD.                ExecuteNonQuery ();            }}} public static object ExecuteScalar (String sql, params sqlparameter[] parameters) { using (SqlConnection conn = new SqlConnection (CONNSTR)) {Conn.                Open (); using (SqlCommand cmd = conn.                    CreateCommand ()) {cmd.commandtext = SQL; Cmd. Parameters.addrange (PARameters); return CMD.                ExecuteScalar (); The SQL public static DataTable executedatatable (String sql, params Sqlpa) is only used to execute query results that are less than                rameter[] Parameters) {using (SqlConnection conn = new SqlConnection (connstr)) { Conn.                Open (); using (SqlCommand cmd = conn.                    CreateCommand ()) {cmd.commandtext = SQL; Cmd.                    Parameters.addrange (Parameters);                    SqlDataAdapter adapter = new SqlDataAdapter (cmd);                    DataSet DataSet = new DataSet (); Adapter.                    Fill (DataSet); return DataSet.                Tables[0]; }            }        }    }}

Package of SqlHelper