求c#高手帮我做一个题目，在线等

（1）σA=D(R×S) A B C D E 4 5 6 4 8 7 8 9 7 5 π3，2 σA=D(R×S) C B 6 5 9 8 （2）不是 （3）create view view2 as select distinct PNO,SNO from SPJ （4）update P set WEIGHT=WEIGHT+100 where PNO='02277' select PNAME from P where PNO='02277'