求解一道数据库的题，用关系代数表达式

Question

如题所述

Answer 1

(1) SELECT T.TNAME,T.TITLE
FROM T INNER JOIN C ON T.T=C.T
WHERE C.CNAME="高等数学"

(2) SELECT DLOOKUP("CNAME","C","C='" & SC.C & "'") AS CNAME

FROM S LEFT JOIN SC ON S.S = SC.S

WHERE S.SNAME="ZHANG" AND SC.S Is Null

(3) SELECT C.CNAME, C.C

FROM C INNER JOIN SC ON C.C = SC.C

WHERE SC.S="S2" OR SC.S="S9"

(4) SELECT S, SNAME
FROM S

WHERE AGE>20 AND SEX="男"本回答被提问者和网友采纳