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-- 单独的截取出年月日--方法一：  extract(year\month\day from sysdate)Select Extract(YEAR from sysdate) from dual;Select Extract(MONTH from sysdate) from dual;Select Extract(DAY from sysdate) from dual;--方法二：to_n...

将表teacher中的name字段 转到 表user中的name字段，限制条件是id为 [2,17]UPDATE user    SET user.name = (SELECT teacher.name FROM teacher WHERE  teacher.number = user.account)     WHERE id BETWEEN 2 AND 17 ;注意：between and 表...