ROUND(TO_NUMBER(结束时间 - 开始时间) * 24)
例:
select avg(ROUND(TO_NUMBER(a.OVER_TIME - a.ASSIGN_TIME) * 24)) as "timeUsed",solveUser.name as "solveUser.name",solveUser.id as "solveUser.id" from em_work_order a
LEFT JOIN sys_user solveUser ON solveUser.id = a.solve_usergroup by solveUser.name,solveUser.id