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這篇文章給大家分享的是有關(guān)Mysq中l(wèi)建立測(cè)試父表、子表及測(cè)試用例的示例的內(nèi)容。小編覺(jué)得挺實(shí)用的,因此分享給大家做個(gè)參考,一起跟隨小編過(guò)來(lái)看看吧。
select version(); 5.7.22
drop table if exists Models; CREATE TABLE Models ( ModelID SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT, Name VARCHAR(40) NOT NULL, PRIMARY KEY (ModelID) );
drop table if exists Orders; CREATE TABLE Orders ( ID SMALLINT UNSIGNED NOT NULL PRIMARY KEY, ModelID SMALLINT UNSIGNED NOT NULL, Description VARCHAR(40), FOREIGN KEY (ModelID) REFERENCES Models (ModelID) ON DELETE cascade );
insert into Orders(Id,ModelID,Description) values (1,1,'a');
結(jié)果:執(zhí)行失敗
異常:[2018-07-31 11:08:01] 23000 Cannot add or update a child row: a foreign key constraint fails (bov
.Orders
, CONSTRAINT Orders_ibfk_1
FOREIGN KEY (ModelID
) REFERENCES Models
(ModelID
) ON DELETE CASCADE)
原因:通不過(guò)on delete cascade 的外鍵約束檢查
insert into Models(ModelID,Name) values (1,'a'); insert into Orders(Id,ModelID,Description) values (1,1,'a');
結(jié)果:執(zhí)行成功
select * from Models; 1 a select * from Orders; 1 1 a
delete from Orders where id = 1;
結(jié)果:執(zhí)行成功
select * from Models; 1 a select * from Orders; 為空
delete from Models where ModelID = 1;
結(jié)果:執(zhí)行成功
select * from Models; 為空 select * from Orders; 為空
update Orders set ModelID = 3 where ID =1;
結(jié)果:執(zhí)行失敗
異常:[2018-07-31 12:33:02] 23000 Cannot add or update a child row: a foreign key constraint fails (bov
.Orders
, CONSTRAINT Orders_ibfk_1
FOREIGN KEY (ModelID
) REFERENCES Models
(ModelID
) ON DELETE CASCADE)
原因:通不過(guò)on delete cascade 的外鍵約束檢查
update Models set ModelID = 2 where ModelID =1;
結(jié)果:執(zhí)行失敗
異常:[2018-07-31 12:34:24] 23000 Cannot delete or update a parent row: a foreign key constraint fails (bov
.Orders
, CONSTRAINT Orders_ibfk_1
FOREIGN KEY (ModelID
) REFERENCES Models
(ModelID
) ON DELETE CASCADE)
原因:通不過(guò)on delete cascade 的外鍵約束檢查
update Orders set Description = 'b' where ID =1;
結(jié)果:執(zhí)行成功
select * from Orders; 1 1 b
update Models set Name = 'c' where ModelID =1;
結(jié)果:執(zhí)行成功
select * from Models; 1 c
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