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[0];
                //不显示最后的空行
                this.dgv_Demo.AllowUserToAddRows = false;
                // 设置第一列只读
                this.dgv_Demo.Columns[0].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(1);
            }
            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 <= 0)
            {
                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;
        }
    }
}