说明: (1)求供应工程J1零件的供应商号码SNO: select sno from spj where jno = J1; (2)求供应工程J1零件P1的供应商号码SNO: select sno from spj where jno =J1 and pno = P1; (3)求供应工程J1零件为红色的供应商号码SNO: select sno from spj natural join p where jno = J1and color = 红; (4)求没有使用天津供应商生产的红 <ghostvater_kun> 在 上传 | 大小:19456