建立测试表
查看版本信息
select version();5.7.22
创建父表
drop table if exists Models;CREATE TABLE Models ( ModelID SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT, Name VARCHAR(40) NOT NULL, PRIMARY KEY (ModelID));
创建子表
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 );
测试
测试用例-无父表相应数据，先插入子表
insert into Orders(Id,ModelID,Description) values (1,1,'a');
结果：执行失败
异常：[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：通不过on delete cascade 的外键约束检查 测试用例-先插入主表数据，再插入子表数据
insert into Models(ModelID,Name) values (1,'a');insert into Orders(Id,ModelID,Description) values (1,1,'a');
结果：执行成功
select * from Models;1 aselect * from Orders;1 1 a
测试用例-父子表都有数据，删除子表数据
delete from Orders where id = 1;
结果：执行成功
select * from Models;1 aselect * from Orders;为空
测试用例-父子表都有数据，删除父表书库
delete from Models where ModelID = 1;
结果：执行成功
select * from Models;为空select * from Orders;为空
测试用例-父子表都有数据，更新子表外键
update Orders set ModelID = 3 where ID =1;
结果：执行失败
异常：[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：通不过on delete cascade 的外键约束检查 测试用例-父子表都有数据，更新父表主键
update Models set ModelID = 2 where ModelID =1;
结果：执行失败
异常：[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：通不过on delete cascade 的外键约束检查 测试用例-父子表都有数据，更新子表非外键
update Orders set Description = 'b' where ID =1;
结果：执行成功
select * from Orders;1 1 b
测试用例-父子表都有数据，更新父表非主键
update Models set Name = 'c' where ModelID =1;
结果：执行成功
select * from Models;1 c