C# → 数据库

  Database：
 public static class dbconnection{
         static string cons = "data source = (local) ;initial catalog = RentManage;integrated security = true;";
         static SqlConnection con = null;
         public static SqlCommand dbconn(string sql, params SqlParameter[] pms)
         {/*连接方法*/
             try{
                 con = new SqlConnection(cons);con.Open();
                 SqlCommand cmd = new SqlCommand(sql, con);
                 if (pms != null){ cmd.Parameters.AddRange(pms); }
                 return cmd;
             }catch {return null; }
         }
         public static int ExecuteNonQuery(string sql, params SqlParameter[] pms)
         {//与执行相关
             SqlCommand cmd = dbconn(sql, pms);
             if (cmd != null){
                 try{ return cmd.ExecuteNonQuery(); }
 catch{ return -;//-1错误码是未查到结果
                 }finally{ if (con != null) con.Close(); }
             }return -;
         }
         public static object ExecuteScalar(string sql, params SqlParameter[] pms)
         {/*登录*/
             object obj = -;//-2错误码是未连接成功
             SqlCommand cmd = dbconn(sql, pms);
             if (cmd != null){
                 try{ obj = cmd.ExecuteScalar();
                 }catch{ obj = -;//-1错误码是未查到结果
                 }finally{ if (con != null) con.Close(); }
             }return obj;
         }
         public static DataTable ExecuteDataTable(string sql, params SqlParameter[] pms)
         { //把查询到的数据填充到表格里
             try{
                 con = new SqlConnection(cons);
                 SqlCommand cmd = new SqlCommand(sql, con);
                 SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                 if (pms != null){
                     adapter.SelectCommand.Parameters.AddRange(pms);
                 }
                 DataSet dataset = new DataSet();
                 adapter.Fill(dataset);
                 return dataset.Tables[];
             }catch (Exception exp){ throw exp;
             }finally{ if (con != null) con.Close(); }
         }
         public static SqlDataReader ExecuteReader(string sql, params SqlParameter[] pms)
         {//读取查询的信息
             SqlCommand cmd = dbconn(sql, pms);
             if (cmd != null){
                 try{
                     return cmd.ExecuteReader(CommandBehavior.CloseConnection);
                 }catch (Exception exp){
                     if (con != null){ con.Close();  }
                     throw exp;
                 }
             }return null;
         }