how to change oldpassword from database in c#

my solution
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SqlConnection connect = new SqlConnection(str);
connect.Open();


string username = label_username.Text;
string password = textBox_Old.Text;
string newPassword = textBox_New.Text;
string confirmPassword = textBox_Verify.Text;
string sqlquery = "UPDATE [Member] SET Password=@newpass where Username=@username";
SqlCommand cmd = new SqlCommand(sqlquery, connect);
cmd.Parameters.AddWithValue("@newpass", textBox_Verify.Text);
cmd.Parameters.AddWithValue("@username", label_username.Text);
cmd.Parameters.AddWithValue("@password", textBox_Old.Text);

cmd.Connection = connect;

cmd.ExecuteNonQuery();

SqlDataReader reader = null;
reader = cmd.ExecuteReader();
while (reader.Read())
{
if ((textBox_New.Text == reader["newPassword"].ToString()) & (textBox_Verify.Text == (reader["confirmPassword"].ToString())))
{

}
}
MessageBox.Show("Password Changed Successfully!");
this.Close();