从 ToDate 获取日期时间对象后，对日期时间对象使用 GetYear(),GetMonth(),GetDay() 并使用 CONCAT 只构造日期.

After you get the datetime object from ToDate, use GetYear(),GetMonth(),GetDay() on the datetime object and use CONCAT to construct only the date.

transf = foreach Source_Data generate  
                   (int) ID, 
                   ToString( ToDate((long) Time_Interval), 'yyyy-MM-dd hh:ss:mm') as TimeStamp,
                   (int) Code;

transf_new = foreach transf generate
                     ID,
                     TimeStamp,
                     CONCAT(CONCAT(CONCAT(GetYear(TimeStamp),'-')),(CONCAT(GetMonth(TimeStamp),'-')),GetDay(TimeStamp)) AS Day,-- Note:Brackets might be slightly off but it should be like 'yyyy-MM-dd' format
                     Code;

-- Now use the new Day column to split the data
SPLIT transf_new INTO       Src25 IF (Day =='2016-07-25'),
                            Src26 IF (Day =='2016-07-26');