急需C#编写的修改登陆密码的代码，大家帮忙啊！

static void Main() 
{
Application.Run(new Form1());
} private void button2_Click(object sender, System.EventArgs e)
{
textBox1.Text=null;
textBox1.Focus();
} private void button1_Click(object sender, System.EventArgs e)
{
string sql="SELECT * FROM adminguanli";
string pw=null;
try
{
thisConnection.Open(); SqlCommand thisCommand=thisConnection.CreateCommand();
thisCommand.CommandText=sql; SqlDataReader thisReader=thisCommand.ExecuteReader(); while(thisReader.Read())
{
pw=thisReader["adminpass"].ToString().Trim();
} thisReader.Close();
thisConnection.Close(); if(textBox1.Text=="")
{
MessageBox.Show("请输入密码！");
textBox1.Focus();
}
else
{
if(pw==textBox1.Text)
{
panel1.Visible=true;
button3.Focus();
}
else
{
MessageBox.Show("您输入的密码不正确，请重新输入！");
textBox1.Text=null;
}
}
}
catch
{
} } private void button3_Click(object sender, System.EventArgs e)
{
this.Hide();
Form2 myForm2=new Form2();
myForm2.ShowDialog();
} private void button4_Click(object sender, System.EventArgs e)
{
panel1.Visible=false;
panel2.Visible=true;
textBox2.Focus();
} private void button6_Click(object sender, System.EventArgs e)
{
textBox2.Text=null;
textBox3.Text=null;
panel2.Visible=false;
panel1.Visible=true;
} private void button5_Click(object sender, System.EventArgs e)
{ if(textBox2.Text.Trim()=="")
{
MessageBox.Show("密码不能为空！");
}
else
{
if(textBox2.Text==textBox3.Text)
{
thisConnection.Open();
                
SqlDataAdapter thisAdapter=new SqlDataAdapter("SELECT * FROM adminguanli",thisConnection);
SqlCommandBuilder thisBuilder=new SqlCommandBuilder(thisAdapter); DataSet thisDataSet=new DataSet(); thisAdapter.Fill(thisDataSet,"adminguanli");
thisDataSet.Tables["adminguanli"].Rows[0]["adminpass"]=textBox2.Text; thisAdapter.Update(thisDataSet,"adminguanli"); thisConnection.Close();
MessageBox.Show("密码修改成功！");
panel2.Visible=false;
panel1.Visible=true;
button3.Focus();
}
else
{
MessageBox.Show("您输入的两次密码不想同，请重新输入！");
textBox2.Text=null;
textBox3.Text=null;
}
}
}