小弟对以下程序遇到点问题
proc SQL;
create volatile table cr_postpayas(
select
charged_party_number
,first_cell_ID,
case
when (day_of_week in (1, 7)) then 'a: Weekend'
when day_of_week not in (1, 7) and Network_Call_Start_Time> '21:59:59'
orNetwork_Call_Start_Time < '06:00:01'
then 'b: Weekdayevening'
when day_of_week not in (1, 7) and Network_Call_Start_Time<= '21:59:59'
orNetwork_Call_Start_Time >= '06:00:01'
then 'c: Weekdaydaytime'
elseend as hours_flag
这个是teradata SQL调数据,但是不知道怎么改使得Network_Call_Start_Time > '21:59:59' 时间可以作比较,因为现在两个值是不一样的类型,有没有人可以帮我一下谢谢了