请大神改造一下我这个sql语句

select ROUND((sum(ORDERAMOUNT)*0.0005),2) as s from boc_payinfo t where 1=1 and mechDate >= '20161001' and mechDate <= '20161003' and PROCSTATE = '04' and ACCCHECKSTATE = '02' and mechno = 00001 group by mechdate

ROUND((sum(ORDERAMOUNT)*0.0005),2) 这句需要用sum包裹，oracle可以，mysql不行，现在需要用MySQl

SELECT sum(t.s) from(
select ROUND((sum(1)*0.0005),2) as s FROM boc_payinfo t where 1=1 and mechDate >= '20161001' and mechDate <= '20161003' and PROCSTATE = '04' and ACCCHECKSTATE = '02' and mechno = 00001 group by mechdate
) t

truncate 直接截取 convert四舍五入

FORMAT((sum(ORDERAMOUNT)*0.0005),2)

ROUND这个函数不是聚合函数 group by 前面需要用聚合函数