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;//-1错误码是未查到结果
                }finally{ if (con != null) con.Close(); }
            }return -2;
        }
        public static object ExecuteScalar(string sql, params SqlParameter[] pms)
        {/*登录*/
            object obj = -2;//-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;//-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[0];
            }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;
        }