DataRowState、AcceptChanges、RejectChanges综合使用示例：实现DataGridView数据的增、删、改

下面的示例中，通过一个程序，演示使用DataRowState、AcceptChanges、RejectChanges，实现DataGridView数据的增、删、改。

一、界面设计

二、代码实现

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

 namespace DataRowStateDemo
 {
     public partial class FrmMain : Form
     {
         public FrmMain()
         {
             InitializeComponent();
         }

         //连接字符串
         string strConn = ConfigurationManager.ConnectionStrings["DbConn"].ConnectionString;

         /// <summary>
         /// 加载
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void btn_LoadData_Click(object sender, EventArgs e)
         {
             Initdgv();
             this.btn_Add.Visible = false;
         }

         /// <summary>
         /// 初始化DataGridView
         /// </summary>
         private void Initdgv()
         {
             SqlConnection conn = new SqlConnection(strConn);
             string strSQL = "select * from Users";
             SqlCommand cmd = new SqlCommand(strSQL, conn);
             SqlDataAdapter adapter = new SqlDataAdapter(cmd);
             DataSet dsDgv = new System.Data.DataSet();
             try
             {
                 conn.Open();
                 //填充数据
                 adapter.Fill(dsDgv);

                 this.dgv_Demo.DataSource = dsDgv.Tables[];
                 //不显示最后的空行
                 this.dgv_Demo.AllowUserToAddRows = false;
                 // 设置第一列只读
                 this.dgv_Demo.Columns[].ReadOnly = true;
             }
             catch (Exception ex)
             { }
             finally
             {
                 conn.Close();
             }
         }

         /// <summary>
         /// 编辑
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void btn_Edit_Click(object sender, EventArgs e)
         {
             this.dgv_Demo.AllowUserToAddRows = true;
         }

         /// <summary>
         /// 保存
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void btn_Save_Click(object sender, EventArgs e)
         {
             DataTable dtCopy = this.dgv_Demo.DataSource as DataTable;
             DataSet dsUsers = new DataSet();

             //产生与表Users结构相同的空表
             DataTable dtAdd = GetEmptyTable();
             DataTable dtEdit = GetEmptyTable();
             DataTable dtDel = GetEmptyTable();

             //根据DataRowState的状态获取新增、修改、删除的表数据
             dtAdd = dtCopy.GetChanges(DataRowState.Added);
             dtEdit = dtCopy.GetChanges(DataRowState.Modified);
             dtDel = dtCopy.GetChanges(DataRowState.Deleted);

             //新增
             if (dtAdd != null)
             {
                 dtAdd.TableName = "Added";
                 dsUsers.Tables.Add(dtAdd);
             }
             //修改
             if (dtEdit != null)
             {
                 dtEdit.TableName = "Edit";
                 dsUsers.Tables.Add(dtEdit);
             }
             //删除
             if (dtDel != null)
             {
                 dtDel.TableName = "Del";
                 dtDel.RejectChanges();
                 dsUsers.Tables.Add(dtDel);
             }
             //保存数据
             if (SaveUser(dsUsers))
             {
                 MessageBox.Show("保存成功!");
                 //重新加载数据
                 Initdgv();
             }
             else
             {
                 MessageBox.Show("保存失败!");
             }
         }

         /// <summary>
         /// 根据表结构产生空表
         /// </summary>
         /// <returns></returns>
         private DataTable GetEmptyTable()
         {
             DataTable dtTable = new DataTable("Users");
             //使用集合初始化器添加列
             dtTable.Columns.AddRange(new DataColumn[]{
                    new DataColumn("UserID",typeof(Int32)),
                    new DataColumn("UserName",typeof(string)),
                    new DataColumn("Password",typeof(string)),
                    new DataColumn("Sex",typeof(Char)),
                    new DataColumn("Birthday",typeof(DateTime))
             });
             return dtTable;
         }

         /// <summary>
         /// 保存数据
         /// </summary>
         /// <param name="ds"></param>
         /// <returns></returns>
         private bool SaveUser(DataSet ds)
         {
             bool tf = false;
             //新增
             if (ds.Tables["Added"] != null)
             {
                 foreach (DataRow dr in ds.Tables["Added"].Rows)
                 {
                    tf= InsertUser(dr);
                 }
             }
             //修改
             if (ds.Tables["Edit"] != null)
             {
                 foreach (DataRow dr in ds.Tables["Edit"].Rows)
                 {
                     tf = UpdateUser(dr);
                 }
             }
             //删除
             if (ds.Tables["Del"] != null)
             {
                 foreach (DataRow dr in ds.Tables["Del"].Rows)
                 {
                     tf = DeleteUser(dr);
                 }
             }
             return tf;
         }

         /// <summary>
         /// 数据库增加
         /// </summary>
         /// <param name="drDataRow"></param>
         /// <returns></returns>
         private bool InsertUser(DataRow drDataRow)
         {
             string strSQL = string.Format(@"insert into users values('{0}','{1}','{2}','{3}')", drDataRow["UserName"].ToString(), drDataRow["Password"].ToString(), 
                                                drDataRow["Sex"].ToString(), drDataRow["Birthday"].ToString());
             return ExecuteSQL(strSQL);
         }

         /// <summary>
         /// 数据库删除
         /// </summary>
         /// <param name="drDataRow"></param>
         /// <returns></returns>
         private bool DeleteUser(DataRow drDataRow)
         {
             string strSQL = string.Format("delete from users where UserID='{0}'", Convert.ToInt32(drDataRow["UserID"].ToString()));
             return ExecuteSQL(strSQL);
         }

         /// <summary>
         /// 数据库修改
         /// </summary>
         /// <param name="drDataRow"></param>
         /// <returns></returns>
         private bool UpdateUser(DataRow drDataRow)
         {
             string strSQL = string.Format("update users set UserName='{0}',Password='{1}',Sex='{2}',Birthday='{3}' where UserID='{4}'",
                                          drDataRow["UserName"].ToString(), drDataRow["Password"].ToString(), drDataRow["Sex"].ToString(),
                                          drDataRow["Birthday"].ToString(), Convert.ToInt32(drDataRow["UserID"].ToString()));
             return ExecuteSQL(strSQL);
         }

          /// <summary>
          /// 数据库执行SQL语句
          /// </summary>
          /// <param name="strSQL"></param>
          /// <returns></returns>
         private bool ExecuteSQL(string strSQL)
         {
             bool tfResult = false;
             SqlConnection conn = new SqlConnection(strConn);
             SqlCommand cmd = new SqlCommand(strSQL, conn);
             try
             {
                 conn.Open();
                 tfResult= cmd.ExecuteNonQuery().Equals();
             }
             catch (Exception ex)
             { }
             finally
             {
                 conn.Close();
             }

             return tfResult;
         }

         /// <summary>
         /// 删除
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void btn_Del_Click(object sender, EventArgs e)
         {
             if (this.dgv_Demo.SelectedRows.Count <= )
             {
                 MessageBox.Show("请先选择要删除的行");
             }
             else
             {
                 foreach(DataGridViewRow dr in this.dgv_Demo.SelectedRows)
                 {
                     //只是删除DataGridView中显示的数据，并没有删除数据库中的数据
                     this.dgv_Demo.Rows.Remove(dr);
                 }

             }
         }

         /// <summary>
         /// 增加空行
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void btn_Add_Click(object sender, EventArgs e)
         {
             //DataGridView没有绑定数据时才可以使用Add()方法增加空行
             this.dgv_Demo.Rows.Add();
         }

         private void FrmMain_Load(object sender, EventArgs e)
         {
             this.dgv_Demo.AllowUserToAddRows = false;
         }
     }
 }