SELECT NOW(); #返回当前系统日期+时间SELECT CURDATE(); #返回当前系统日期,无时间SELECT CURTIME(); #返回当前系统时间，不包括日期SELECT YEAR(NOW()); #返回年SELECT YEAR(CURDATE()); #返回年SELECT YEAR('1999-1-1'); #返回年SELECT MONTH(NOW()); #返回月SELECT MONTHNAME(NOW()); #返回当前月的英文名称SELECT DAY(NOW()); #返回日SELECT HOUR(NOW()); #返回时SELECT MINUTE(NOW()); #返回分SELECT SECOND(NOW()); #返回秒SELECT STR_TO_DATE ('1999-1-1','%Y-%m-%d'); #按照字符串格式解析时间#案例:查询入职日期为1992-4-3的员工信息SELECT * FROM employees WHERE hiredate='1992-4-3';SELECT * FROM employees WHERE hiredate= STR_TO_DATE('4-3-1992','%m-%d-%Y');SELECT DATE_FORMAT(NOW(),'%y年%m月%d日') AS out_put; #将日期解析成字符串格式#案例：查询有奖金员工的员工名和入职日期(月/日 年)SELECT last_name, DATE_FORMAT(hiredate,'%m月/%d日 %Y年')FROM employeesWHERE commission_pct>0;