wtuqi
3/18/2020 - 2:22 AM

约束

References.sql
content_copyfile_download
--外键约束
Pnum varchar(12) constraint Fk_Pn foreign key(Pnum) references pro_table(Pnum),
Fnum varchar References pro_table(Fnum),
--添加外键约束
alter table Tool
add constraint Fk_PD foreign key(Pnum) references pro_table(Pnum)