A. Case  Grade    When  90~100  THEN ’优’     When  80~89  THEN ’良’     When  70~79  THEN ’中’      When  60~69  THEN ’及格’      Else  ’不及格’      End
B. Case     When  Grade  between 90  and  100  THEN  Grade = ’优’      When  Grade  between 80  and  89  THEN  Grade = ’良’      When  Grade  between 70  and  79  THEN  Grade = ’中’      When  Grade  between 60  and  69  THEN  Grade = ’及格’      Else  Grade = ’不及格’      End
C. Case     When  Grade  between  90  and  100  THEN  ’优’      When  Grade  between  80  and  89  THEN  ’良’      When  Grade  between  70  and  79  THEN  ’中’      When  Grade  between  60  and  69  THEN  ’及格’      Else  ’不及格’      End
D.Case Grade  When 90~100  THEN  Grade = ’优’   When 80~89  THEN  Grade = ’良’   When 70~79  THEN  Grade = ’中’   When 60~69  THEN  Grade = ’及格’    Else  Grade = ’不及格’    End