SqlDataAdapter、DataSet、DataTable使用

            try 

            { 

                conn = new SqlConnection(connString); 

                // create data adapter   

                SqlDataAdapter da = new SqlDataAdapter(sql, conn); 

                // create and fill data set   

                DataSet ds = new DataSet(); 

                /* 

                 * 如果SqlDataAdapter对应的sql语句返回多个数据集， 

                 * 则SqlDataAdapter对应的DataTable名 

                 * 会被依次命名为"Table", "Table1","Table2"…… 

                 * 如下调用得到的将会把"Table"对应着"Customers"，

                 * "Table1"对应着"Products"                  

                 */ 

                da.TableMappings.Add("Table", "Customers"); 

                da.TableMappings.Add("Table1", "Products"); 

                da.Fill(ds); 

                // get the data tables collection   

                DataTableCollection dtc = ds.Tables; 

                //输出DataTableCollection中所有表的表名。   

                System.Console.WriteLine("DataTable in the DataTableCollection: "); 

                foreach (DataTable dt in dtc) 

                { 

                    System.Console.WriteLine("\t{0}", dt.ToString()); 

                } 

                // display data from first data table   

                //   

                // display output header   

                System.Console.WriteLine("Results from Customers table:"); 

                System.Console.WriteLine( 

                   "CompanyName".PadRight(20) + 

                   "ContactName".PadLeft(23) + "\n"); 

                // set display filter   

                string fl = "country = ‘Germany‘"; 

                // set sort   

                string srt = "companyname asc"; 

                foreach (DataRow row in dtc["Customers"].Select(fl, srt))   //  dtc["Customers"] 是DataTable , 看为内存的一张数据库表 ， 按照条件+排序查询

                { 

                    System.Console.WriteLine( 

                       "{0}\t{1}", 

                       row["CompanyName"].ToString().PadRight(25), 

                       row["ContactName"]); 

                } 

                // display data from second data table   

                //   

                // display output header   

                System.Console.WriteLine("\n----------------------------"); 

                System.Console.WriteLine("Results from Products table:"); 

                System.Console.WriteLine( 

                   "ProductName".PadRight(20) + 

                   "UnitPrice".PadLeft(21) + "\n"); 

                //下句中dtc["Products"]中还可以按照表索引值访问，等价于dtc[1]   

                foreach (DataRow row in dtc["Products"].Rows) 

                { 

                    System.Console.WriteLine("{0}\t{1}", 

                       row["productname"].ToString().PadRight(25), 

                       row["unitprice"]); 

                } 

            } 

            catch (System.Exception e) 

            { 

                System.Console.WriteLine("Error: " + e); 

            } 

            finally 

            { 

                // close connection   

                conn.Close(); 

            } 

        } 

    } 

}

SqlDataAdapter、DataSet、DataTable使用

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