mysql函数

select LENGTH(os.order_sub_no),CONCAT(SUBSTR(os.order_sub_no,1,LENGTH(os.order_sub_no)-1),0)
from tbl_order_sub os 
where os.id = 'e7345bd7dfd142fb99dcce6bdb695101'

concat,substr,length

DELETE t1, t2 FROM t1, t2, t3 WHERE t1.id=t2.id AND t2.id=t3.id;

连表删除，只删除t1,t2中的数据