DataGridView连接Sql数据库 功能 查询 添加 删除 修改

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace _03大项目
{
    public partial class Form1 : Form
    {
        //连接字符串
        string str = "Data Source=.;Initial Catalog=MyDeskInfo;Integrated Security=True";
        public Form1()
        {
            InitializeComponent();
        }
        //窗体加载
        private void Form1_Load(object sender, EventArgs e)
        {
            //加载餐桌
            LoadDeskInfoByDelFlag(0);
        }
        /// <summary>
        /// 该方法是加载所有没有被删除的餐桌
        /// </summary>
        /// <param name="p">删除标识 0---未删除,1---删除</param>
        private void LoadDeskInfoByDelFlag(int p)
        {
            List<DeskInfo> list = new List<DeskInfo>();


            //通过连接字符串连接数据库
            using (SqlConnection con = new SqlConnection(str))
            {
                //拼接sql语句
                string sql = "select DeskId,DeskName,DeskNamePinYin,DeskNum from DeskInfo where DeskDelFlag=" + p;
                //准备执行sql语句的对象
                using (SqlCommand cmd = new SqlCommand(sql, con))
                {
                    con.Open();//打开数据库
                    //准备读数据
                    using (SqlDataReader reader = cmd.ExecuteReader())
                    {
                        //判断是否有数据(有没有行)
                        if (reader.HasRows)
                        {
                            //读取每一行
                            while (reader.Read())
                            {
                                DeskInfo dk = new DeskInfo();//创建餐桌对象
                                dk.DeskId = Convert.ToInt32(reader["DeskId"]);//id
                                dk.DeskName = reader["DeskName"].ToString();//名字
                                dk.DeskNamePinYin = reader["DeskNamePinYin"].ToString();//拼音
                                dk.DeskNum = reader["DeskNum"].ToString();//编号
                                list.Add(dk);//添加到集合中
                            }//end while
                        }//end if
                    }// end sqldatareader
                }//end using
            }//end using


            dgv.AutoGenerateColumns = false;//禁止自动生成列
            dgv.DataSource = list;//绑定数据 到集合list，这样才有显示
            dgv.SelectedRows[0].Selected = false;//禁止被选中

        }
        //添加数据
        private void btnOk_Click(object sender, EventArgs e)
        {
            int n = -1;
            //获取文本框的值
            //连接数据库
            using (SqlConnection con = new SqlConnection(str))
            {
                string sql = string.Format("insert into DeskInfo(DeskName, DeskNamePinYin, DeskDelFlag, DeskNum) values('{0}','{1}',{2},'{3}')", txtName.Text, txtPinYin.Text, 0, txtNum.Text);
                using (SqlCommand cmd = new SqlCommand(sql, con))
                {
                    con.Open();//打开数据库
                    n = cmd.ExecuteNonQuery();
                }
            }
            string msg = n > 0 ? "操作成功" : "操作失败";
            MessageBox.Show(msg);
            LoadDeskInfoByDelFlag(0);//刷新

        }

        private void btnDelete_Click(object sender, EventArgs e)
        {

            //判断一下 是否选中行
            if (dgv.SelectedRows.Count > 0)
            {
                int r = -1;
                //选中了
                //该行数据的id
                string strId = dgv.SelectedRows[0].Cells[0].Value.ToString();
                int id = Convert.ToInt32(strId);//转换一下
                //update DeskInfo set DeskDelFlag=1 where DeskId=

                using (SqlConnection con = new SqlConnection(str))
                {
                    string sql = "update DeskInfo set DeskDelFlag=1 where DeskId=" + id;
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    {
                        con.Open();
                        r = cmd.ExecuteNonQuery();
                    }// end using 
                }//end using

                string msg = r > 0 ? "操作成功" : "操作失败";
                MessageBox.Show(msg);
                LoadDeskInfoByDelFlag(0);//刷新
            }
        }

        private void dgv_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (dgv.SelectedRows.Count>0)
            {
                //获取这条数据中的每个列中的值
                //id  name  pinyin  num
                labId.Text = dgv.SelectedRows[0].Cells[0].Value.ToString();
                txtUName.Text = dgv.SelectedRows[0].Cells[1].Value.ToString();
                txtUPinYin.Text = dgv.SelectedRows[0].Cells[2].Value.ToString();
                txtUNum.Text = dgv.SelectedRows[0].Cells[3].Value.ToString();
            }
           


        }

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            if (dgv.SelectedRows.Count>0)
            {
                int r = -1;
                //修改
                using (SqlConnection con=new SqlConnection(str))
                {
                    string sql =string.Format("update DeskInfo set DeskName='{0}',DeskNamePinYin='{1}',DeskNum='{2}' where DeskId={3}",txtUName.Text,txtUPinYin.Text,txtUNum.Text,Convert.ToInt32(labId.Text));
                    using (SqlCommand cmd=new SqlCommand(sql,con))
                    {
                        con.Open();
                       r= cmd.ExecuteNonQuery();
                    }// end using
                }// end using
                MessageBox.Show(r>0?"操作成功":"操作失败");
                LoadDeskInfoByDelFlag(0);
            }
        }
        //显示有多少条数据
        private void button1_Click(object sender, EventArgs e)
        {
            //不要这个
            //MessageBox.Show(dgv.SelectedRows.Count);

            //练习
            object obj;
            using (SqlConnection con=new SqlConnection(str))
            {
                string sql = "select count(*) from DeskInfo where DeskDelFlag=0";
                using (SqlCommand cmd=new SqlCommand(sql,con))
                {
                    con.Open();
                    obj= cmd.ExecuteScalar();
                }
            }
            MessageBox.Show(obj.ToString());

        }

        private void btnGc_Click(object sender, EventArgs e)
        {
            //查询的是被删除的数据
            LoadDeskInfoByDelFlag(1);
        }

        private void btnCDDelete_Click(object sender, EventArgs e)
        {
            string id = dgv.SelectedRows[0].Cells[0].Value.ToString();
            //还是 更新  改标识   5 恢复 数据需要再交钱 100 超邪恶的方法
            //稍稍的修改一下标识  
            //  如果有一天 我邪恶了 请记住 我曾纯洁过             

            int r = -1;
            //修改
            using (SqlConnection con = new SqlConnection(str))
            {
                string sql = "update DeskInfo set DeskDelFlag=5";
                using (SqlCommand cmd = new SqlCommand(sql, con))
                {
                    con.Open();
                    r = cmd.ExecuteNonQuery();
                }// end using
            }// end using
            MessageBox.Show(r > 0 ? "操作成功" : "操作失败");
        }
    }
}