这些是我的表格:
CREATE TABLE EMPLOYEE(
Emp_id number(4),
Emp_name varchar2(30),
Emp_gender varchar2(1),
Status varchar2(30),
Years_service number(4),
Primary Key (emp_id)
);
CREATE TABLE ACTIVITY(
Act_id number(4),
Description varchar2(30),
Category_code varchar2(1),
Primary Key(Act_id)
);
CREATE TABLE ALLOCATION(
Emp_id number(4) NOT NULL,
Act_id number(4) NOT NULL,
Hourly_rate number(5,2) NOT NULL,
Primary Key (Act_id, Emp_id),
Foreign Key (Act_id) REFERENCES ACTIVITY,
Foreign Key (Emp_id) REFERENCES EMPLOYEE,
CONSTRAINT CK_ALLOCATION_RATE CHECK(Hourly_rate > 0 and Hourly_rate<300)
);
CREATE TABLE ACTION(
Week_no number(2) NOT NULL,
Hrs_worked number(4,1) NOT NULL,
Act_id number(4) NOT NULL,
emp_id number(4) NOT NULL,
Primary Key (Week_no, Act_id, emp_id),
Foreign Key (Act_id) References Allocation,
Foreign Key (emp_id) References Allocation
);
完整地创建了表格employee
,activity
和allocation
。但是当我尝试创建表action
并将外键引用到表allocation
时,它会说: ORA-02256:引用列的数量必须与引用的列匹配。
答案 0 :(得分:1)
使用references
时,我认为在两个表中包含列是个好主意,即使语法不必要(默认是主键)。 / p>
您有一个复合主键,因此您需要一个外部引用的复合键:
CREATE TABLE ACTION (
Week_no number(2) NOT NULL,
Hrs_worked number(4,1) NOT NULL,
Act_id number(4) NOT NULL,
emp_id number(4) NOT NULL,
Primary Key (Week_no, Act_id, emp_id),
Foreign Key (Act_id, emp_id) References Allocation(Act_id, emp_id)
);