CREATE TABLE "U_WEN_BOOK"."FARTAB" ("FAR_ID" NUMBER(10) NOT NULL,
"FAR_NAME" VARCHAR2(10),"OTHER_NAME" VARCHAR2(10),
CONSTRAINT "PK_FER" PRIMARY KEY("FAR_ID"))

CREATE TABLE "U_WEN_BOOK"."CHILTAB" ("CHIL_ID" NUMBER(10) NOT
NULL,"CHIL_NAME" VARCHAR2(10),"CHIL_OTHER" VARCHAR2(10),
"FAR_ID" NUMBER(10) NOT NULL,
CONSTRAINT "PK_CHIL" PRIMARY KEY("CHIL_ID"),
CONSTRAINT "FK_CHIL" FOREIGN KEY("FAR_ID")
REFERENCES "U_WEN_BOOK"."FARTAB"("FAR_ID") ON DELETE CASCADE)

ALTER TABLE "U_WEN_BOOK"."GCHILTAB1"
DROP CONSTRAINT "FK_G1"
ALTER TABLE "U_WEN_BOOK"."GCHILTAB1"
ADD (CONSTRAINT "FK_G1" FOREIGN KEY()
REFERENCES "U_WEN_BOOK"."CHILTAB"()
ON DELETE CASCADE)
（这样就可以级联删除了，删除完后，如果不放心这样的约束条件，并且不嫌麻烦可以再重建为不带级联删除等外键约束，防止误操作）

create table orderCombine (
O_Id VARCHAR2(16) not null,
OrderId VARCHAR2(15) not null,
FormerId VARCHAR2(16) not null,
constraint PK_ORDERCOMBINE primary key (FormerId) );
create table VIPForm (
V_Id VARCHAR2(16) not null,
IsValid CHAR(1) default '0' not null,
Constraint fk_vipform foreign key(V_id) references ordercombine(formerid) );
insert into orderCombine values('1','1','1'); insert into orderCombine values('2','2','2'); insert into vipform values('1','5'); insert into vipform values('2','4'); insert into vipform values('1','2');

CREATE OR REPLACE TRIGGER "FG123"."TER_OV"
BEFORE
DELETE ON "ORDERCOMBINE" FOR EACH ROW
BEGIN
DELETE FROM VIPForm
WHERE VIPForm.V_Id=:OLD.FormerId;
END;

DELETE FROM "FG123"."ORDERCOMBINE"
WHERE FormerId ='1'

DELETE FROM "FG123"."ORDERCOMBINE"
WHERE VIPForm ='1'；

DELETE FROM "FG123"."ORDERCOMBINE"
WHERE FormerId ='1'