删除数据总是失败
public class PersonOperate
{
public PersonOperate()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
  public static bool FindPerson(int pID)//建立静态方法查找用户是存在(int pID)
  {
  SqlConnection conn = DB.conCreate();
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  cmd.CommandText = "select count(*) from test where pID='" + pID + "'";
  //cmd.CommandText = "select count(*) from adonettest where UserName='" +username+ "'";
  cmd.Connection = conn;
  int count = Convert.ToInt32(cmd.ExecuteScalar());
  if (count > 0)//表示用户已经存在
  {
  return true;
  }
  else
  {
  return false;//可以注册,数据库目前还没有该用户
  }
   
  }
  public static bool InsertOperate(Person insert)//建立插入数据的静态方法
  {
  try
  {
  SqlConnection conn = DB.conCreate();
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  //cmd.CommandText = "insert into adonettest values(@pID,@pName,@pSex)";
  cmd.CommandText = "insert into test values(@pID,@pName,@pSex)";
  cmd.Connection = conn;
  SqlParameter para = new SqlParameter("@pID", SqlDbType.Int);//插入姓名
  para.Value = insert.pID;//把Poerson类声明的变量pID赋给para
  cmd.Parameters.Add(para);
  para = new SqlParameter("@pName", SqlDbType.VarChar, 50);//插入密码
  para.Value = insert.pName;//把Poerson类声明的变量pName赋给para
  cmd.Parameters.Add(para);
  //para = new SqlParameter("@pPwd", SqlDbType.VarChar, 20);
  //para.Value = insert.pUserPwd;
  //cmd.Parameters.Add(para);
  para = new SqlParameter("@pSex", SqlDbType.VarChar, 2);//选择性别
  para.Value = insert.pSex;//把Poerson类声明的变量pSex赋给para
  cmd.Parameters.Add(para);
  //cmd.ExecuteScalar();
  cmd.ExecuteNonQuery();
  conn.Close();
  return true;
  }
  catch (Exception ex)
  {
  return false;
  }
  }
  public static DataTable SelectAllPoerson()//建立查询用户的静态方法
  {
  SqlConnection conn = DB.conCreate();
  conn.Open();
  SqlDataAdapter sda=new SqlDataAdapter();
  sda.SelectCommand = new SqlCommand("select * from test", conn);
  DataSet ds = new DataSet();
  sda.Fill(ds, "table");
  return ds.Tables["table"];
   

  }
  public static bool DelOperate(int pID)//建立删除用户的方法
  {
  try
  {

  SqlConnection conn = DB.conCreate();
  conn.Open();
  SqlCommand cmd = new SqlCommand("delete from test where pID='" + pID + "'");
  cmd.ExecuteNonQuery();
  conn.Close();
  conn.Dispose();
  return true;
  }
  catch (Exception ex)
  {
  return false;
  }
  }
  public static bool UpdateOperate(Person update)//建立更新