零基础开发--歌曲管理系统

   本文主要是从头开始讲如何创建一个项目，本文以创建一个歌曲管理系统为例。

  首先创建数据库：MyMusic（我的音乐）

  其中添加表：SongInformation（歌曲信息表）

if DB_ID('MyMusic') is not null
drop database MyMusic
go
create database MyMusic  --创建MyMusic（我的音乐）数据库
on
(
name=MyMusic,
filename='D:CS架构学习窗体DBMyMusic.mdf'
)
--打开数据库
use MyMusic
--创建表歌曲
if OBJECT_ID('SongInformation') is not null
drop table SongInformation --歌曲信息表
go
create table SongInformation 
(
  Songid int primary key identity(10000,1),  --编号
  SongName varchar(50) not null,   --歌名
  Singer varchar(50) not null,  --演唱者
  Album varchar(50)  --专辑
)
--查询表SongInformation
select *from SongInformation
--添加测试数据
insert SongInformation select '演员','薛之谦','绅士'union
select '尽头','赵方倩','音阙诗听'union
select '当你','王心凌','遇上爱'union
select '七里香','周杰伦','七里香'union
select '微微一笑很倾城','杨洋','微微一笑很倾城'union
select '岁月神偷','金玟岐','金玟岐作品集'union
select '带你去旅行','校长','带你去旅行'

创建主窗口：FrmMain(歌曲信息管理系统

创建窗口：歌曲修改（增加）窗口FrmModifySong

准备工作 --建立帮助类：DBHelper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Data;
using System.Data.SqlClient;

namespace 窗口
{
 public   class DBHelper
    {
        public static string ConStr = "server=.;uid=sa;pwd=sa;database=MyMusic";
        public  static SqlConnection con = null;

        #region 创建连接对象
        public  static SqlConnection GetConnection()
        {
            if (con == null || con.ConnectionString == "")
            {
                con = new SqlConnection(ConStr);
            }
            return con;
        } 
        #endregion
        #region 打开连接
        public static void OpenConnection()
        {
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
        }
        #endregion
        #region 关闭连接
        public static void CloseConnection()
        {
            if (con.State == ConnectionState.Open)
            {
                con.Close();
            }
        }
        #endregion
        #region 查询多行多列的值
        public static SqlDataReader ExecuteReader(string sql,
            params SqlParameter [] para)
        {
            SqlConnection con = GetConnection();
            OpenConnection();
            SqlCommand com = new SqlCommand(sql, con);
         
            com.Parameters.AddRange(para);
            SqlDataReader dr = com.ExecuteReader();
            return dr;
        }
        #endregion
        #region 动作查询
        public static int ExecuteNonQuery(string sql,
           params SqlParameter[] para)
        {
            SqlConnection con = GetConnection();
            OpenConnection();
            SqlCommand com = new SqlCommand(sql, con);       
            com.Parameters.AddRange(para);
            int n = com.ExecuteNonQuery();
            CloseConnection();
            return n;
        }

       
        #endregion

    }
}

建立实体类：Song（对应数据库中的表SongInformation）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 窗口
{
  public  class Song
    {
        public int Songid { get; set; }
        public string SongName { get; set; }
        public string Singer { get; set; }
        public string Album { get; set; }
    }
}

然后实现窗体加载功能（将数据加载到DataGirdView中）

  #region 将后台信息加载到网格
        private void LoadDOV(string sql)
        {
            if (sql == "")
            {
                sql = "select*from SongInformation";
            }
            SqlConnection con = new SqlConnection(DBHelper.ConStr);
            SqlDataAdapter sda = new SqlDataAdapter(sql, con);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            dgvSong.DataSource = dt;
        }
        #endregion

        #region 窗体加载事件方法
        private void FrmMain_Load(object sender, EventArgs e)
        {
            LoadDOV("");
        }
        #endregion

实现查询功能：

 #region 查询事件方法
        private void btnQuery_Click(object sender, EventArgs e)
        {
            string sql = "select*from SongInformation where 1=1";
            if (txtSongName.Text != "")
            {
                sql += "and SongName like '%" + txtSongName.Text + "%'";
            }
            if (txtSinger.Text != "")
            {
                sql += "and Singer like '%" + txtSinger.Text + "%'";
            }
            LoadDOV(sql);
        }

        #endregion

  最后！也是难点！传参，将DataGridView中的数据传到FrmModifySong窗口中对应的Textbox中

 首先创建实体操作类SongManage

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Data.SqlClient;

namespace 窗口
{
    public class SongManage
    {
        //传参
        public static List<Song> SelectCarsAll()
        {
            List<Song> song = new List<Song>();
            string sql = "select*from SongInformation";
            SqlDataReader dr = DBHelper.ExecuteReader(sql);
            while (dr.Read())
            {
                Song songs = new Song();
                songs.Songid = Convert.ToInt32(dr["Songid"]);
                songs.SongName = Convert.ToString(dr["SongName"]);
                songs.Singer = Convert.ToString(dr["Singer"]);
                songs.Album = Convert.ToString(dr["Album"]);
                song.Add(songs);
            }
            dr.Close();
            DBHelper.CloseConnection();
            return song;
        }

        //修改
        public static Song SelectCarsByCarId(int Songid)
        {
            Song song = null;
            string sql = "select * from SongInformation where Songid=" + Songid;
            SqlDataReader dr = DBHelper.ExecuteReader(sql);
            if (dr.Read())
            {
                song = new Song();
                song.Songid = Convert.ToInt32(dr["Songid"]);
                song.SongName = Convert.ToString(dr["SongName"]);
                song.Singer = Convert.ToString(dr["Singer"]);
                song.Album = Convert.ToString(dr["Album"]);

            }
            dr.Close();
            DBHelper.CloseConnection();
            return song;
        }

        //添加
        public static int InsertSong(Song song)
        {
            string sql = string.Format("insert  SongInformation (SongName,Singer,Album) values('{0}','{1}','{2}')", song.SongName, song.Singer, song.Album);
            return DBHelper.ExecuteNonQuery(sql);
            
        }

        //更新
        public static int UpdateSong(Song song)
        {
            string sql = "update SongInformation set SongName=@SongName,Singer=@Singer,Album=@Album where Songid=@Songid";
            return DBHelper.ExecuteNonQuery(sql,new SqlParameter[] 
            {
                new SqlParameter("@SongName",song.SongName),
                new SqlParameter("@Singer",song.Singer),
                new SqlParameter("@Album",song.Album),
                new SqlParameter("@SongId",song.Songid),
            });
        }
    }
}

然后回到主窗口FrmMain中创建修改、添加的方法

  #region 修改
        /// <summary>
        /// 修改事件方法
        /// </summary>
        private void TsmModify_Click(object sender, EventArgs e)
        {
            if (dgvSong.SelectedRows.Count > 0)
            {
                int Songid = (int)dgvSong.SelectedRows[0].Cells["Songid"].Value;
                FrmModifySong frm = new FrmModifySong();
                frm.Songid = Songid;
                frm.ShowDialog();
            }
        }
        #endregion

   #region 添加事件方法
        private void tsmAdd_Click(object sender, EventArgs e)
        {
            FrmModifySong frm = new FrmModifySong();          
            frm.Show();
        } 
        #endregion

然后回到歌曲添加（删除）窗口FrmModifySong实现保存功能和取消功能

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;

namespace 窗口
{
    public partial class FrmModifySong : Form
    {
        public int Songid { get; set; }
        private string type = "添加";
        public FrmModifySong()
        {
            InitializeComponent();
        }

        #region 取消按钮事件方法
        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }
        #endregion

        #region 保存按钮事件方法
        private void btnSave_Click(object sender, EventArgs e)
        {
            Song song = new Song
            {    
                SongName=txtSongName.Text,
                Singer=txtSinger.Text,
                Album=txtAlbum.Text            
            };
            int n = 0;
            if (type == "添加")
            {
                n = SongManage.InsertSong(song);
            }
            else
            {
                song.Songid = Songid;
                n = SongManage.UpdateSong(song);
            }

            if (n > 0)
            {
                MessageBox.Show(type + "成功！");
                                                   
            }
            else
            {
                MessageBox.Show(type + "失败！");
            }
        }
        #endregion

        private void FrmModifySong_Load(object sender, EventArgs e)
        {
            if (Songid != 0)
            {
                type = "修改";
               txtSongid.ReadOnly = true;
                Song song = SongManage.SelectCarsByCarId(Songid);
                if (song != null)
                {
                    txtSongid.Text = song.Songid.ToString();
                    txtSongName.Text = song.SongName;
                    txtSinger.Text = song.Singer;
                    txtAlbum.Text = song.Album;
                }
                this.Text = "修改歌曲信息";
            }
            else
            {
                txtSongid.ReadOnly = false;
                this.Text = "添加歌曲信息";
            }
        }
    }
}

最后实现删除功能

  #region 删除事件方法
        //删除事件方法
        private void TsmDelete_Click(object sender, EventArgs e)
        {
            int Songid = (int)dgvSong.SelectedRows[0].Cells[0].Value;
            string sql = "delete SongInformation  where SongId=" + Songid;
            int n = DBHelper.ExecuteNonQuery(sql);
            if (n > 0)
            {
                MessageBox.Show("删除成功", "删除提示");
                LoadDOV("");
            }
            else
            {
                MessageBox.Show("删除失败", "删除提示");
            }
        } 
        #endregion

OK，一个简单的项目就这么完成了！