实验7 ADO.NET管理数据库

概述

这里我选择使用的源数据库是vs2019自带的sqlserver。
如何创建：点击跳转
注意细节，如果要将id设置为自增字段，需要改这里

好了，进入正题：

代码以及运行截图 1. 实现数据库的增删查改功能 (1)注册(向数据库中添加记录)

乱码参考：点击跳转
运行截图：

(2)登录(从数据库中查询记录)，要求采用DataReader对象。

(3)修改密码(修改数据库中的记录)

(4)注销(删除数据库中的记录)

代码：

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Windows.Forms;
namespace WebApplication6
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"insert into person (username,password) values ("+"'"+username+"'"+","+"'"+password+"'"+")";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            sqlCommand.ExecuteNonQuery();
        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"select password from person where username="+"'"+username+"'";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            SqlDataReader reader = sqlCommand.ExecuteReader();
            string password1="";
            if (reader.Read())
                password1 = reader.GetString(0);
            if (password.Equals(password1)) {
                MessageBox.Show("登录成功");
            }
        }

        protected void Button3_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"update person set password=" + "'" + password + "' " + "where username='" + username+"'";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            sqlCommand.ExecuteNonQuery();
        }

        protected void Button4_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"delete from person where username='" + username + "'";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            sqlCommand.ExecuteNonQuery();
        }
    }
}

2. 采用ExecuteScalar方法，改写（2）中登录功能的代码。

如何弹出消息框，参考：点击跳转

代码：

protected void Button2_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"select password from person where username="+"'"+username+"'";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            string password1 = (string)sqlCommand.ExecuteScalar();
            if (password.Equals(password1)) {
                MessageBox.Show("登录成功");
            }
        }

3. 采用DataAdapter对象和DataSet对象，改写（2）中登录功能的代码。

代码：

 protected void Button2_Click(object sender, EventArgs e)
        {
            string username = TextBox1.Text;
            string password = TextBox2.Text;
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql = @"select password from person where username="+"'"+username+"'";
            SqlDataAdapter da = new SqlDataAdapter(sql, con);
            DataSet ds = new DataSet();
            da.Fill(ds, "person");
            string password1 = "";
            foreach (DataRow row in ds.Tables[0].Rows)
            {
                password1 = row[0].ToString();
            }
            if (password.Equals(password1)) {
                MessageBox.Show("登录成功");
            }
        }

4. 首先附加“IPAddress”数据库到SQL Server2008中，数据库中“IP”表的结构如图27所示，部分数据如图28所示，建立如图所示的页面，输入IP地址，将查询结果显示在Label控件中，如图29所示，要求采用DataReader对象。

代码：

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication5
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            string connString = @"Data Source=(localdb)MSSQLLocalDB;Initial Catalog=Test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
            SqlConnection con = new SqlConnection(connString);
            con.Open();
            string sql= @"select * from IPAddress";
            SqlCommand sqlCommand = new SqlCommand(sql, con);
            SqlDataReader reader = sqlCommand.ExecuteReader();
            string or = TextBox1.Text;
            while (reader.Read())
            {
                string start= reader.GetString(0);
                string end = reader.GetString(1);
                if (or.CompareTo(start) >= 0 && or.CompareTo(end) <= 0) {
                    Label1.Text = reader.GetString(2);
                    break;
                }
            }
        }
    }
}