sql的使用

1.自动获取最新订单号

     

select concat('XJDD',DATE_FORMAT(now(),'%Y%m%d'),
   LPAD((if(max(SUBSTRING(inquirynum FROM 13 FOR 4)) is null,1,
   max(SUBSTRING(inquirynum FROM 13 FOR 4))+1)),4,'0')) as Newnum  
   from ip_c_inquiry where SUBSTRING(inquirynum FROM 5 FOR 8)=DATE_FORMAT(now(),'%Y%m%d')