mysql日期操作技巧

mysql 获取当年第一天的年月日格式：
SELECT DATE_SUB(CURDATE(),INTERVAL dayofyear(now())-1 DAY);
MySQL里获取当前week、month、quarter的第一天/最后一天  
   
当前week的第一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 1 DAY)  
   
当前week的最后一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) – 5 DAY)  
   
前一week的第一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 8 DAY)  
   
前一week的最后一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 2 DAY)  
   
前两week的第一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 15 DAY)  
   
前两week的最后一天：  
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 9 DAY)  
当前month的第一天：  
SELECT concat(date_format(LAST_DAY(now()),’%Y-%m-’),’01′)  
   
当前month的最后一天：  
SELECT LAST_DAY(now())  
   
前一month的第一天：  
SELECT concat(date_format(LAST_DAY(now() – interval 1 month),’%Y-%m-’),’01′)