REFERENCES ref_table [ ( ref_column ) ex:
job_id smallint NOT NULL
DEFAULT 1
REFERENCES jobs(job_id)CONSTRAINT FK_sales_backorder FOREIGN KEY (stor_id, ord_num, title_id)
REFERENCES sales (stor_id, ord_num, title_id)
job_id smallint NOT NULL
DEFAULT 1
REFERENCES jobs(job_id)CONSTRAINT FK_sales_backorder FOREIGN KEY (stor_id, ord_num, title_id)
REFERENCES sales (stor_id, ord_num, title_id)
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CONSTRAINT table2 FOREIGN KEY (userID)
REFERENCES table1 (ID)在table1中:
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constraint table1 primary key (ID)
references table2(userID)
你明白了吗?