計算Oracle兩個TIMESTAMP相差的毫秒數

CREATE OR REPLACE FUNCTION uf_timestamp_diff(endtime in TIMESTAMP,starttime in TIMESTAMP)

RETURN INTEGER

AS

 str VARCHAR2(50);

 misecond INTEGER;

 seconds INTEGER;

 minutes INTEGER;

 hours INTEGER;

 days INTEGER;

BEGIN

 str:=to_char(endtime-starttime);

 misecond:=to_number(SUBSTR(str,INSTR(str,' ')+10,3));

 seconds:=to_number(SUBSTR(str,INSTR(str,' ')+7,2));

 minutes:=to_number(SUBSTR(str,INSTR(str,' ')+4,2));

 hours:=to_number(SUBSTR(str,INSTR(str,' ')+1,2));

 days:=to_number(SUBSTR(str,1,INSTR(str,' ')));

 RETURN days*24*60*60*1000+hours*60*60*1000+minutes*60*1000+seconds*1000+misecond;

END;