[英]Creating SQL table, foreign_key confusion
One question, I have supervisor set as foreign key. 一个问题,我将主管设置为外键。 He collect information through Activity Participant and take it from person ID. 他通过活动参与者收集信息,并从人员ID中获取信息。
Question: 题:
How should I create the Activity
table? 我应该如何创建Activity
表? what do I have to write down about supervisor? 我要写下有关主管的内容吗?
CREATE TABLE activity
(
act_id VARCHAR(8) CONSTRAINT activity_pk PRIMARY KEY,
act_type VARCHAR2(20),
act_desc VARCHAR2(30),
act_date DATE,
mor_aft VARCHAR2(9),
CONSTRAINT activity_sup_fk FOREIGN KEY (act_supVisor) REFERENCES person()
);
A foreign key must reference a unique key of the referenced table. 外键必须引用被引用表的唯一键。 Either the table's primary key, or else a secondary unique key. 表的主键或辅助唯一键。
CONSTRAINT activity_sup_fk FOREIGN KEY (act_supVisor)
REFERENCES person(Person_id)
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