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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 RLHT_YXJ_WFA1
{
??? public partial class LogIn : Form
??? {
??????? //string[] table=new string[20];
??????? public LogIn()
??????? {
??????????? InitializeComponent();
??????? }
??????? private void button1_Click(object sender,EventArgs e)
??????? {
??????????? using (SqlConnection conn = new SqlConnection(@"Data Source=YXJSQLEXPRESS;AttachDBFilename=|DataDirectory|Ceshi.mdf;Integrated Security=True;User Instance=true"))
??????????? {
??????????????? conn.Open();
??????????????? using (SqlCommand cmd = conn.CreateCommand())
??????????????? {
??????????????????? cmd.CommandText="select user_name,user_pwd from Users Where user_name='"+this.textBox1.Text+"'";
??????????????????? using (SqlDataReader reader = cmd.ExecuteReader())
??????????????????? {
??????????????????????? if (this.textBox1.Text == "")
??????????????????????????? MessageBox.Show("请输入您的用户名");
??????????????????????? else if (this.textBox2.Text == "")
??????????????????????????? MessageBox.Show("请输入您的密码");
??????????????????????? else if (reader.Read())
??????????????????????? {
??????????????????????????? //用户名存在
??????????????????????????? string dbpassword = reader.GetString(reader.GetOrdinal("user_pwd"));
??????????????????????????? if (this.textBox2.Text == dbpassword)
??????????????????????????? {
??????????????????????????????? //登陆成功
??????????????????????????????? ShowUser showuser = new ShowUser(textBox1.Text);
??????????????????????????????? showuser.Show();
??????????????????????????? }
??????????????????????????? else
??????????????????????????? {
??????????????????????????????? //密码错误
??????????????????????????????? MessageBox.Show("您所输入的密码错误");
??????????????????????????????? this.textBox2.Text = null;
??????????????????????????? }
??????????????????????? }
??????????????????????? else
??????????????????????? {
??????????????????????????? //用户名错误
??????????????????????????? MessageBox.Show("您所输入的用户名不存在");
??????????????????????????? this.textBox1.Text = null;
??????????????????????? }
??????????????????? }
??????????????? }
??????????????? conn.Close();
??????????????? conn.Dispose();
??????????? }
??????
??????????? //数据访问出现问题，明明修改了数据库，但还是可以用修改前的老用户数据进行访问，是缓存问题？有知道的高手烦请解答。
??????????? //DataTable table = new DataTable();
??????????? //SqlDataAdapter da = new SqlDataAdapter();
??????????? //string connstr = @"Data Source=YXJSQLEXPRESS;AttachDBFilename=|DataDirectory|Ceshi.mdf;Integrated Security=True;User Instance=true";
??????????? //SqlConnection connection = new SqlConnection(connstr);
??????????? //connection.Open();
??????????? //SqlCommand ca = new SqlCommand("select user_name,user_pwd from Users Where user_name='"+this.textBox1.Text+"'",connection);
??????????? //da.SelectCommand = ca;
??????????? //da.Fill(table);
??????????? //if (this.textBox1.Text == "")
??????????????
??????????? //??? MessageBox.Show("请输入您的用户名");
??????????? //else if (this.textBox2.Text == "")
??????????? //??? MessageBox.Show("请输入您的密码");
??????????? //else if (table.Rows.Count == 0)
??????????? //{
??????????? //??? MessageBox.Show("您所输入的用户名不存在");
??????????? //??? this.textBox1.Text = null;
??????????? //}
??????????? //else if (table.Rows[0][0].ToString() != this.textBox2.Text)
??????????? //{
???????????????
??????????? //??? MessageBox.Show("您所输入的密码错误");
??????????? //??? this.textBox2.Text = null;
??????????? //}
??????????? //else
??????????? //{
??????????? //??? System.Console.WriteLine(table.Rows[0][0].ToString());
??????????? //??? System.Console.WriteLine(this.textBox2.Text);
??????????? //??? MessageBox.Show(table.Rows[0][0].ToString());
??????????? //??? MessageBox.Show(this.textBox2.Text);
??????????? //??? ShowUser showuser = new ShowUser(textBox1.Text);
??????????? //??? showuser.Show();
??????????? //}
??????????? //connection.Close();
??????????? //table.Clear();
??????????
??????? }
??????? private void button3_Click(object sender,EventArgs e)
??????? {
??????????? NewUser newuser=new NewUser();
??????????? newuser.Show();
??????? }
??????? private void button4_Click(object sender,EventArgs e)
??????? {
??????????? textBox1.Clear();
??????????? textBox2.Clear();
??????? }
??????? private void button2_Click(object sender,EventArgs e)
??????? {
??????????? this.Close();
??????? }
??? }
}
参考：
SqlDataAdapter
http://baike.baidu.com/view/2978109.htm
DataTable
http://www.voidcn.com/article/p-xydzoirt-s.html
?
关于|DataDirectory|：
Program.cs
?static void Main()
??????? {
??????????? string dataDir = AppDomain.CurrentDomain.BaseDirectory;
??????????? if (dataDir.EndsWith(@"binDebug") || dataDir.EndsWith(@"binRelease"))
??????????? {
??????????????? dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;
??????????????? AppDomain.CurrentDomain.SetData("DataDirectory",dataDir);
??????????? }
??????????? Application.EnableVisualStyles();
??????????? Application.SetCompatibleTextRenderingDefault(false);
??????????? Application.Run(new LogIn());
??????? }
//这是为了在测试运行的时候，让项目里的数据库文件和程序Debug或Release运行里的数据库文件区别开，真正交付给客户的时候一般不需要这段代码。
（编辑：李大同）
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