3月12日 增删改查

初始数据库

winform设计图

以面向对象的思想，先封装两个类：userDate类存属性，userDA类存方法

userDate类：

public class userDate
    {
        private int _code;

        public int Code                //封装类
        {
            get { return _code; }
            set { _code = value; }
        }
        private string _uname;

        public string Uname
        {
            get { return _uname; }
            set { _uname = value; }
        }
        private string _upass;

        public string Upass
        {
            get { return _upass; }
            set { _upass = value; }
        }
    }

userDA类：

class userDA
    {
        private SqlConnection _Conn;
        private SqlCommand _Cmd;

        public userDA()
        {
            _Conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=sa");
        }
        //添加   
        public void Insert(userDate data)
        {
        }
        //修改
        public void Update(userDate data)
        {
        }
        //删除
        public void Delete(int code)
        {
        }
        //查询全部
        public List<userDate> Select2()
        {
         }
        //按用户名查询
        public List<userDate> Select2(string uname)
        {
         }
    }

一、增加：

核心代码：

点击添加时：

private void button1_Click(object sender, EventArgs e)
       {
           userDate data = new userDate();

           data.Uname = textBox2.Text;
           data.Upass = textBox1.Text;

           new userDA().Insert(data);
       }

userDA类中：Insert方法

public void Insert(userDate data)
        {
            _Conn.Open();
            _Cmd = _Conn.CreateCommand();
            _Cmd.CommandText = "insert into table1 VALUES (@uname, @upass)";

            _Cmd.Parameters.Clear();
            _Cmd.Parameters.Add("@uname",data.Uname);
            _Cmd.Parameters.Add("@upass",data.Upass);
            _Cmd.ExecuteNonQuery();
            _Conn.Close();
        }

1. 点增加                                            2.查询一下，添加上了

   

3.数据库里有了

二、查询：

核心代码：

点击查询时：

private void select2_Click(object sender, EventArgs e)
        {
           List<userDate> list= new userDA().Select2(textBox1.Text);
            Binding(list);
        }

//封装数据函数

private void Binding(List<userDate> list)
       {
           listView1.Columns.Clear();

           listView1.Columns.Add("编号");
           listView1.Columns.Add("用户名");
           listView1.Columns.Add("密码");

           listView1.Items.Clear();

           foreach (userDate date in list)
           {
               ListViewItem lt = new ListViewItem();
               lt.Text = date.Code.ToString();
               lt.SubItems.Add(date.Uname);
               lt.SubItems.Add(date.Upass);

               listView1.Items.Add(lt);
           }
       }

userDA类中：两个查询函数（重载）

     //查询全部
       public List<userDate> Select2()
       {
           List<userDate> list=new List<userDate>();

           _Conn.Open();
           _Cmd = _Conn.CreateCommand();
           _Cmd.CommandText = "select*from table1";

           SqlDataReader dr = _Cmd.ExecuteReader();

           while (dr.Read())
           {
               userDate data = new userDate();
               data.Code = int.Parse(dr["code"].ToString());
               data.Uname = dr["uname"].ToString();
               data.Upass = dr["upass"].ToString();

               list.Add(data);
           }

            return list;
       }
       //按用户名查询（条件查询）
       public List<userDate> Select2(string uname)
       {
           List<userDate> list = new List<userDate>();

           _Conn.Open();
           _Cmd = _Conn.CreateCommand();
           _Cmd.CommandText = "select * from table1 where uname like '%"+uname+"%'";

           SqlDataReader dr = _Cmd.ExecuteReader();

           while (dr.Read())
           {
               userDate data = new userDate();
               data.Code = int.Parse(dr["code"].ToString());
               data.Uname = dr["uname"].ToString();
               data.Upass = dr["upass"].ToString();

               list.Add(data);
           }

           return list;
       }

1.全部显示：                                           2.按用户名模糊查询

      

三、修改

核心代码：

点击时：

private void button1_Click(object sender, EventArgs e)
       {
           userDate data = new userDate();

           data.Code = int.Parse(textBox3.Text);
           data.Uname = textBox2.Text;
           data.Upass = textBox1.Text;

           new userDA().Update(data);
       }

userDA类中：

public void Update(userDate data)
    {
        _Conn.Open();
        _Cmd = _Conn.CreateCommand();
        _Cmd.CommandText = "update table1 set uname='"+data.Uname+"',upass='"+data.Upass+"' where code="+data.Code;

        _Cmd.ExecuteNonQuery();
        _Conn.Close();
    }

1.点击修改                                         2.查询后改变了                                 3。数据库也变了

       

四、删除

核心代码：

点击时：

private void delete1_Click(object sender, EventArgs e)
       {
           if (listView1.SelectedItems.Count > 0)  // SelectedItems选中项
           {
               int code = int.Parse(listView1.SelectedItems[0].Text);
               new userDA().Delete(code);
           }
           else
           {
               MessageBox.Show("请先选中，再删除！");
           }
           List<userDate> list = new userDA().Select2();
           Binding(list);
       }

userDA类：

public void Delete(int code)
        {
            _Conn.Open();
            _Cmd = _Conn.CreateCommand();
            _Cmd.CommandText = "delete from table1 where code="+code;

            _Cmd.ExecuteNonQuery();

            _Conn.Close();
        }

1.点击删除时：                                     2.点击删除后：