根據(jù)CJB輸出各課程的平均成績對應等級來定義學習難度:(平均成績)80分以上者為“易學課”,70分以上者為“普通難度課”,70分以下者為“難學課”。查詢結果中包含“課程號”、“學習難度等級”兩列。類似的內(nèi)容為: 課程號 其對應的SQL語句為:SELECT課程號, 學習難度等級 = __①__ FROM CJB __②__ 上述語句的空項內(nèi)容為()
A.a B.b C.c D.d
A. SET @Cjb_Cur = CURSOR FOR SELECT * FROM CJB B. CREATE @CURSOR Cjb_Cur AS SELECT * FROM CJB C. DECLARE @Cjb_Cur AS TABLE CJB D. DECLARE @Cjb_Cur CURSOR FOR SELECT * FROM CJB
A. DECLARE Kcb_Cur CURSOR FOR SELECT * FROM KCB B. SET Kcb_Cur = CURSOR FOR SELECT * FROM KCB C. CREATE CURSOR Kcb_Cur AS SELECT * FROM KCB D. DECLARE Kcb_Cur AS TABLE KCB