[C#] 检索数据库并用DataGridView 控件显示数据.

练习点:

数据库读取数据并保存在一个集合中.

使用DataGridView来显示数据.

1 Form1 用于用户登录验证



Form1 Code

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;

namespace DataGridViewTest2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
string username = txtUsername.Text;
string password = txtPassword.Text;

DBConnect dbc = new DBConnect();

int s = dbc.UserLogin(username, password);

if (1 == s)
{
MessageBox.Show("Incorrect Username");
}
if (2 == s)
{
MessageBox.Show("Incorrect Password");
}
if(0 == s)
{
Form2 form2 = new Form2(this);
//this.Hide();
form2.ShowDialog();
}

}
}
}

2. Form2, 用记显示数据, 它只有一个DataGridView控件



Form2 Code

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.Collections;

namespace DataGridViewTest2
{
public partial class Form2 : Form
{
Form1 form1;
public Form2(Form1 form1)
{
InitializeComponent();
this.form1 = form1;
}

private void Form2_Load(object sender, EventArgs e)
{
DBConnect dbc = new DBConnect();
ArrayList UserList = new ArrayList();

UserList = dbc.ExportData();
UserList.Reverse();

//DataGridView设置
DataTable DataTable1 = new DataTable();
DataTable1.Columns.AddRange(new DataColumn[] { new DataColumn("ID"), new DataColumn("Name"), new DataColumn("Sex"), new DataColumn("Age"), new DataColumn("Address") });

foreach (User users in UserList)
{

DataTable1.Rows.Add(users.Id, users.Username, users.Sex==0?"男":"女" , users.Age, users.Address);
}

dataGridView1.DataSource = DataTable1;
}

}
}

3. BDConnect.cs, 数据库链接, 用于验证和提取数据

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Collections;

namespace DataGridViewTest2
{
class DBConnect
{
string username, password;

public int UserLogin(string username, string password)
{
this.username = username;
this.password = password;

//下面这段文字的作用已经在其它博文中解释!
string dataDir = AppDomain.CurrentDomain.BaseDirectory;
if (dataDir.EndsWith(@"\bin\Debug\")
|| dataDir.EndsWith(@"\bin\Release\"))
{
dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;
AppDomain.CurrentDomain.SetData("DataDirectory", dataDir);
}

using(SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\UserInfo.mdf;Integrated Security=True;User Instance=True"))
{
conn.Open();

using(SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT * FROM UserLogin WHERE username='"+username + "'";

using(SqlDataReader reader = cmd.ExecuteReader())
{
if(!reader.Read())
{
return 1;//没有此用户
}
else
{
string dbpassword = reader.GetString(reader.GetOrdinal("password"));
if(dbpassword != password)
{
return 2;//用户密码不对
}
else
{
return 0;
}
}
}
}
}
}

public ArrayList ExportData()
{
ArrayList UserList = new ArrayList();

//下面这段文字的作用已经在其它博文中解释!
string dataDir = AppDomain.CurrentDomain.BaseDirectory;
if (dataDir.EndsWith(@"\bin\Debug\")
|| dataDir.EndsWith(@"\bin\Release\"))
{
dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;
AppDomain.CurrentDomain.SetData("DataDirectory", dataDir);
}

using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\UserInfo.mdf;Integrated Security=True;User Instance=True"))
{
conn.Open();

using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT * FROM UserInfo";

using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
User users = new User();
users.Id = (int)reader[0];
users.Username = (string)reader[1];
users.Sex = (int)reader[2];
users.Age = (int)reader[3];
users.Address = (string)reader[4];

UserList.Add(users);
}
}

}

}

return UserList;
}
}
}

4. Users.cs, 用于存储数据

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

namespace DataGridViewTest2
{
class User
{
private int id, sex, age;
private string username, address;

public int Id
{
get { return id; }
set { id = value; }
}

public int Sex
{
get { return sex; }
set { sex = value; }
}

public int Age
{
get { return age; }
set { age = value; }
}

public string Username
{
get { return username; }
set { username = value; }
}

public string Address
{
get { return address; }
set { address = value; }
}
}
}

5. 数据库 的两个表

UserLogin



UserInfo



6. 登录成功后显示的结果如下:



update:

从数据库里提取信息的代码有所更新, 使用 SqlDataAdapter来查询数据,并将数据填充到DataTable里反回给DataGridView里显示.

public DataTable ExportData()
{
DataTable UserTable = new DataTable();
using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\UserInfo.mdf;Integrated Security=True;User Instance=True"))
{
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT * FROM UserInfo";
using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
{
SqlDataAdapter.Fill(UserTable)
}
}
}
return UserTable;
}
}
}