1.建立四個表:
create table client(
c_id int identity(1,1),
c_name nvarchar(255) unique,
c_pass nvarchar(255),
c_sex bit,
c_mail varchar(255),
c_qq varchar(255),
primary key(c_id)
);
create table album_kind(
k_id int identity(1,1),
k_name nvarchar(255),
k_desc nvarchar(255),
primary key(k_id)
);
create table album(
a_id int identity(1,1),
a_name nvarchar(255),
a_desc nvarchar(255),
a_create_date datetime,
a_times bigint,
c_id int,
k_id int,
primary key(a_id),
foreign key(c_id) references client(c_id) on delete cascade,
foreign key(k_id) references album_kind(k_id) on delete cascade
);
create table album_word(
aw_id int identity(1,1),
aw_title nvarchar(255),
aw_content nvarchar(500),
commit_date datetime,
a_id int,
c_id int,
primary key(aw_id),
foreign key(a_id) references album(a_id) on delete cascade,
foreign key(c_id) references client(c_id) on delete cascade
);
這時(創(chuàng)建第四個表的時候)sqlserver2000會報告錯誤:
將 FOREIGN KEY 約束 'FK_album_word_album' 引入表 'album_word' 中將導(dǎo)致循環(huán)或多重級聯(lián)路徑??荚嚧筇崾菊堉付?ON DELETE NO ACTION 或 ON UPDATE NO ACTION,或修改其它 FOREIGN KEY 約束。[Microsoft][ODBC SQL Server Driver][SQL Server]未能創(chuàng)建約束。請參閱前面的錯誤信息。
2.這時候我們?nèi)サ舻谒膫€表中的級聯(lián)刪除:
"on delete cascade"
再次執(zhí)行。。。。通過
3.創(chuàng)建一個觸發(fā)器可以解決這個問題(接以上1.2步):
CREATE TRIGGER album_word_client ON client
FOR INSERT, UPDATE, DELETE
AS
delete album_word from album_word join deleted on album_word.c_id = deleted.c_id
完成!
語法:
create trigger 隨便一個名稱(比如b_a) on 表a
for delete
as
delete 表b from 表b join deleted on 表b.a表外鍵=deleted.a表主鍵
(當(dāng)刪除a中某條記錄,b中相關(guān)聯(lián)記錄也會相應(yīng)刪除)
create table client(
c_id int identity(1,1),
c_name nvarchar(255) unique,
c_pass nvarchar(255),
c_sex bit,
c_mail varchar(255),
c_qq varchar(255),
primary key(c_id)
);
create table album_kind(
k_id int identity(1,1),
k_name nvarchar(255),
k_desc nvarchar(255),
primary key(k_id)
);
create table album(
a_id int identity(1,1),
a_name nvarchar(255),
a_desc nvarchar(255),
a_create_date datetime,
a_times bigint,
c_id int,
k_id int,
primary key(a_id),
foreign key(c_id) references client(c_id) on delete cascade,
foreign key(k_id) references album_kind(k_id) on delete cascade
);
create table album_word(
aw_id int identity(1,1),
aw_title nvarchar(255),
aw_content nvarchar(500),
commit_date datetime,
a_id int,
c_id int,
primary key(aw_id),
foreign key(a_id) references album(a_id) on delete cascade,
foreign key(c_id) references client(c_id) on delete cascade
);
這時(創(chuàng)建第四個表的時候)sqlserver2000會報告錯誤:
將 FOREIGN KEY 約束 'FK_album_word_album' 引入表 'album_word' 中將導(dǎo)致循環(huán)或多重級聯(lián)路徑??荚嚧筇崾菊堉付?ON DELETE NO ACTION 或 ON UPDATE NO ACTION,或修改其它 FOREIGN KEY 約束。[Microsoft][ODBC SQL Server Driver][SQL Server]未能創(chuàng)建約束。請參閱前面的錯誤信息。
2.這時候我們?nèi)サ舻谒膫€表中的級聯(lián)刪除:
"on delete cascade"
再次執(zhí)行。。。。通過
3.創(chuàng)建一個觸發(fā)器可以解決這個問題(接以上1.2步):
CREATE TRIGGER album_word_client ON client
FOR INSERT, UPDATE, DELETE
AS
delete album_word from album_word join deleted on album_word.c_id = deleted.c_id
完成!
語法:
create trigger 隨便一個名稱(比如b_a) on 表a
for delete
as
delete 表b from 表b join deleted on 表b.a表外鍵=deleted.a表主鍵
(當(dāng)刪除a中某條記錄,b中相關(guān)聯(lián)記錄也會相應(yīng)刪除)