MySQL time-to-reduce notation

Select *  from  (  select  c.ordernumber,   c.name as equipmentname,    A. *,   d.starttime, d.endtime,  (select DateDiff (D.starttime, D.endtime)) as lev ,  case (select DateDiff (D.starttime, d.endtime))   When (select DateDiff (D.starttime, d.endtime)) <=10  Then ' Emergency Repair '   when  10< (select DateDiff (D.starttime, d.endtime)) <=30 then  ' expected repair '    else ' no maintenance ' end as   levname   from  cloud_componentlist a     left join     cloud_ Equipmentcomponen b  on  a.id= b.component   left join   cloud_equipment C on C. Equipmentid = b.equipmentid   Left join    (SELECT * from cloud_componentrepairrecord  limit 0, 1 ORDER by CreateDate desc ) d    on d.cloud_componentid= a.id where  1=1   order by Le V desc )   a  limit 0,10;&NBSP;&NBSP;&NBSp

MySQL time-to-decrement