第18题: [单项选择]从student表删除年龄大于30的记录的正确SQL命令是( )。 A. DELETE FOR年龄>30 B. DELETE FROM student WHERE年龄>30 C. DELETE student FOR年龄>30 D. DELETE student WHERE年龄>30 参考答案:B 答案解析:【解析】删除所需条件的记录格式为DELETE FROM Table_name[WHERE Condition],所以答案为B。
第31题: [单项选择]A fog signal consisting of one prolonged blast followed by four short blasts would indicate thepresence of a(). A. vessel being towed B. fishing vessel engaged in trawling C. vessel at anchor warning of her location D. power-driven pilot vessel on station underway 参考答案:D