设有学生表S(SNO,SN)(SNO为学生号,SN为姓名)答:(1)create view V_ssc(SNO,SN,CNO,CN,C)as select S.SNO,SN,CNO,CN,C from S,SC where S.SNO=SC.SNO order by CNO asc (2)select SN,CN,C from V_SSC group by SNO having avg(C)>90
数据库SQL语言答:设有一个工程供应数据库系统,包括如下四个关系模式:lS(SNO,SNAME,STATUS,CITY);lP(PNO,PNAME,COLOR,WEIGHT);lJ(JNO,JNAME,CITY);lSPJ(SNO,PNO,JNO,QTY);供应商表S由... 设有一个工程供应数据库系统,包括如下四个关系模式:l S(SNO,SNAME, STATUS,CITY);l P(PNO,PNAME,COLOR,WEIGHT);l J(JNO,J...