Methods:

1. Delete all foreign key constraints

2. drop form

3. Add foreign key constraints Code generated using powerdesign

/*==============================================================*/
/* DBMS name:   ORACLE Version 10g              */
/* Created on:   2013/8/16 14:30:03              */
/*==============================================================*/


alter table Da_pic
  drop constraint FK_DA_PIC_REFERENCE_DA_PICSU;

drop table Da_pic cascade constraints;

drop table Da_picsubject cascade constraints;

/*==============================================================*/
/* Table: Da_pic                        */
/*==============================================================*/
create table Da_pic (
  ID          VARCHAR2(200)          not null,
  no          VARCHAR2(200),
  subjiectid      VARCHAR2(200),
  Name         VARCHAR2(400),
  UploadTime      DATE,
  UserId        VARCHAR2(200),
  picdate       DATE,
  place        VARCHAR2(200),
  people        VARCHAR2(200),
  event        VARCHAR2(200),
  background      VARCHAR2(200),
  cameramen      VARCHAR2(200),
  serial        INTEGER,
  IsEffect       VARCHAR2(200),
  constraint PK_DA_PIC primary key (ID)
);

/*==============================================================*/
/* Table: Da_picsubject                     */
/*==============================================================*/
create table Da_picsubject (
  ID          VARCHAR2(200)          not null,
  no          VARCHAR2(200),
  title        VARCHAR2(200),
  year         VARCHAR2(200),
  type         VARCHAR2(200),
  gdtime        DATE,
  iseffect       VARCHAR2(200),
  seiral        INTEGER,
  constraint PK_DA_PICSUBJECT primary key (ID)
);

alter table Da_pic
  add constraint FK_DA_PIC_REFERENCE_DA_PICSU foreign key (subjiectid)
   references Da_picsubject (ID);