Question

这是我用于创建表employee的create table命令，但即使我已将ssn声明为主键，我也无法弄清楚为什么会出现此错误

CREATE TABLE EMPLOYEE(
F_NAME VARCHAR2(15) NOT NULL,
M_NAME CHAR(2),
L_NAME VARCHAR2(15) NOT NULL,
SSN CHAR(9) PRIMARY KEY,
BIRTHDAY DATE,
ADDRESS VARCHAR2(50),
SEX CHAR(1) CHECK(SEX IN('M','F','m','f')),
SALARY NUMBER(7) DEFAULT 800,
SSSN CHAR(9),
DEPARTMENT_NUMBER NUMBER(5),
CONSTRAINT EMP_SSSN_FK FOREIGN KEY(SSSN)
REFERENCES EMPLOYEE(SSSN) ON DELETE SET NULL,
CONSTRAINT EMP_DEPTNO_FK FOREIGN KEY(DEPARTMENT_NUMBER)
REFERENCES DEPARTMENT(DEPT_NO) ON DELETE CASCADE);

但我收到错误：

ORA-02270: no matching unique or primary key for this column-list

Answer 1

将CONSTRAINT EMP_SSSN_FK FOREIGN KEY(SSSN)更改为CONSTRAINT EMP_SSSN_FK FOREIGN KEY(SSN)，如下所示：

CREATE TABLE EMPLOYEE(
F_NAME VARCHAR2(15) NOT NULL,
M_NAME CHAR(2),
L_NAME VARCHAR2(15) NOT NULL,
SSN CHAR(9) PRIMARY KEY,
BIRTHDAY DATE,
ADDRESS VARCHAR2(50),
SEX CHAR(1) CHECK(SEX IN('M','F','m','f')),
SALARY NUMBER(7) DEFAULT 800,
SSSN CHAR(9),
DEPARTMENT_NUMBER NUMBER(5),
CONSTRAINT EMP_SSSN_FK FOREIGN KEY(SSSN) REFERENCES EMPLOYEE(SSN) ON DELETE SET NULL,
CONSTRAINT EMP_DEPTNO_FK FOREIGN KEY(DEPARTMENT_NUMBER) REFERENCES DEPARTMENT(DEPT_NO) ON DELETE CASCADE);

Answer 2

当且仅当它是另一个表中的主键时，才能在表中声明外键。您需要立即执行的操作是确保SSN和DEPARTMENT_NUMBER是其各自表中的主键。

访问此链接，您将很容易找到错误。 http://www.techonthenet.com/oracle/errors/ora02270.php

如果您不遵循，请继续学习 http://www.w3schools.com/sql/sql_foreignkey.asp

希望有所帮助

创建表时出现ORA-02270错误

2 个答案: