将STUDENT表中NL列的值都更新为20岁，正确 的SQL语句是（ ）
A.UPDATE STUDENT SET NL=21 B.SET STUDENT UPDATE NL=20 C.UPDATE STUDENT SET NL=20 D.INSERT INTO STUDENT SET NL=20正确答案C
将STUDENT表中NL列的值都更新为20岁，正确 的SQL语句是（ ）
A.UPDATE STUDENT SET NL=21 B.SET STUDENT UPDATE NL=20 C.UPDATE STUDENT SET NL=20 D.INSERT INTO STUDENT SET NL=20正确答案C
