oracle 时间差

//计算毫秒差(两个date类型的相减为天数差别，然后转换为毫秒)

select ceil(to_date('209-11-17 13:00:12','yyyy-mm-dd hh24:mi-ss')-to_date(2009-11-18 14:00:12','yyyy-mm-dd hh24:mi-ss') )from dual;

//计算相差月份

select (EXTRACT(year from to_date('209-11-17','yyyy-mm-dd'))-EXTRACT(year fromto_date('2009-11-18','yyyy-mm-dd') ))*12+(EXTRACT(month from to_date('209-11-17','yyyy-mm-dd'))-EXTRACT(month fromto_date('2009-11-18','yyyy-mm-dd') ))from dual;

//通过时间戳运算

select to_timestamp('2009-11-17 19:20:12 234','yyyy-mm-dd hh24:mi:ss ff')-to_timestamp('2009-11-16 11:12:34 167','yyyy-mm-dd hh24:mi:ss ff') from dual;

返回值为+000000010 00:02:24.00000000 字符串要转换为毫秒数字，自定义函数实现

//自定义用时间戳运算函数

create or replace function TIME_INTERVAL(endTime varchar2,startTime varchar2)

return number

IS

p_1 varchar2(40);

begin

p_1 := to_timestamp(endTime,'yyyy-mm-dd hh24:mi:ss ff')-to_timestamp(startTime,'yyyy-mm-dd hh24:mi:ss ff');

return trunc(to_number(substr((p_1),1,instr(p_1,' '))))*24*60*60+to_number(substr((p_1),instr((p_1),' ')+1,2))*60*60+to_number(substr((p_1),instr((p_1),' ')+4,2))*60+to_number(substr((p_1),instr((p_1),' ')+7,2));

end;