4.1.SELECT SNO FROM SPJ WHERE JNO='J1' 4.2.SELECT SNO FROM SPJ WHERE JNO='J1' AND PNO='P1' 4.3.SELECT SNO FROM SPJ,P WHERE SPJ.PNO=P.PNO AND COLOR='红' AND JNO='J1' OR:SELECT SNO FROM SPJ WHERE JNO='J1' AND PNO IN (SELECT PNO FROM P WHERE COLOR='红')