3_05_MSSQL课程_Ado.Net_SQLDataAdapter

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Configuration;
 using System.Data;
 using System.Data.SqlClient;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;

 namespace _01SQLAndAdo.Net
 {
     public partial class SqlData2DataGirdView : Form
     {
         public SqlData2DataGirdView()
         {
             InitializeComponent();
         }

         private void SqlData2DataGirdView_Load(object sender, EventArgs e)
         {

             string connStr = ConfigurationManager.ConnectionStrings["sql"].ConnectionString;
             string commandText = @"SELECT TOP 1000 [User_ID]
                                     ,[User_Name]
                                     ,[User_Gender]
                                     ,[User_Age]
                                     ,[User_Address]
                                     ,[User_Birthday]
                                     ,[User_Remark]
                                     ,[User_Money]
                                     ,[User_GUIDDemo]
                                     ,[User_Pwd]
                                      FROM[LJK_SQLServerDB].[dbo].[User_Info]";
             using (SqlConnection conn = new SqlConnection(connStr))
             {
                 using (SqlDataAdapter adapter = new SqlDataAdapter(commandText, connStr))
                 {
                     //DataSet方式，查询多张表的时候应用
                     //DataSet dataSet=new DataSet();
                     //adapter.Fill(dataSet,"demo");
                     //this.dgvUserInfo.DataSource = dataSet.Tables["demo"];

                     DataTable dataTable = new DataTable();
                     //填充之前不需要打开数据库连接，Adaper会自动打开连接，并执行SQL
                     //Fill方法内部：
                     //1. 先判断SqlConnection是否初始化，如果没有打开链接，那么打开连接。
                     //2. 初始化一个Select(commandText) SqlCommand对象
                     //3. 通过cmd对象执行，然后返回一个SqlReader对象。
                     //4. 读取数据库中的数据，然后填充到DataTable上去
                     adapter.Fill(dataTable); //把数据库中的数据 填充到 内存表中
                     //把内存表显示到DataGirdView上去
                     // this.dgvUserInfo.DataSource = dataTable;

                     // var o = dataTable.Rows[0][1];

                     // dataRow["列名"];       //弱类型
                     //user.UserInfo           //强类型，出错概率下降
                     List<UserInfo> userInfoList = new List<UserInfo>();
                     foreach (DataRow dataRow in dataTable.Rows)
                     {
                         Console.WriteLine(dataRow["User_Id"] + "         " + dataRow[]);
                         Console.WriteLine(dataRow["User_Name"] + "         " + dataRow[]);
                         Console.WriteLine(dataRow["User_Age"] + "         " + dataRow[]);
                         Console.WriteLine(dataRow["User_Pwd"] + "         " + dataRow[]);
                         UserInfo userInfo = new UserInfo();
                         userInfo.UserId = int.Parse(dataRow["User_ID"].ToString());
                         userInfo.UserName = dataRow["User_Name"].ToString();
                         if (!string.IsNullOrEmpty(dataRow["User_Age"].ToString()))
                         {
                             userInfo.UserAge = int.Parse(dataRow["User_Age"].ToString());
                             // userInfo.UserAge = dataRow["User_Age"].ToString();
                             // userInfo.UserAge = 1;
                         }
                         else
                         {
                             userInfo.UserAge = ;
                         }

                         if (!string.IsNullOrEmpty(dataRow["User_Pwd"].ToString()))
                         {
                             userInfo.UserPwd = int.Parse(dataRow["User_Pwd"].ToString());
                         }
                         else
                         {
                             userInfo.UserPwd = ;
                         }

                         userInfoList.Add(userInfo);

                         //把DataTabel的数据转成List<UserInfo>

                     }

                     this.dgvUserInfo.DataSource = userInfoList;

                 }

             }

         }
     }
 }