CREATE TABLE insured_autos (
policy_id NUMBER CONSTRAINT policy_fk REFERENCE policies(policy_id ON DELETE CASCADE,vin VARCHAR2(40),coverage_begin DATE,coverage_term NUMBER,make VARCHAR2(30),model VARCHAR(30),year NUMBER,CONSTRAIN auto_fk FROEIGN KEY (make,model,year) REFERENCES automobiles (make,model,year) ON DELETE SET NULL);
其中,各个字段的含义是什么啊? 请高手指教!多谢!!
请问vin是哪个单词的缩写啊?肯定表示供应商么?
coverage_begin,日期 coverage_term,数字 这两个字段的含义有代表什么呢?