如何在PL/SQL

Question

比較時間戳我有這樣的說法：

create table times (time_in timestamp, time_out timestamp); 
insert into times values(to_timestamp('02-MAY-11 07.57.00.000000 AM'), to_timestamp('02-MAY-11 07.30.00.000000 PM')); 
select extract(hour from(time_out-time_in))||':'||extract(minute from(time_out-time_in)) from times; 

EXTRACT(HOURFROM(TIME_OUT-TIME_IN))||':'||EXTRACT(MINUTEFROM(TIME_OUT-TIME_IN)) 
--------------------------------------------------------------------------------- 
11:33 

而現在，我想比較上面的結果。例如：IF [result] > [8 hours] THEN ...

如何做到這一點？

Answer 1

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一個PL/SQL程序，這將是這樣的內幕：

declare 
    result interval day to second; 
begin 

    -- !!! make sure this select returns only one row, or use a cursor !!! 
    select time_out - time_in 
    into result 
    from times; 

    if (result > interval '8' hour) then 
    dbms_output.put_line('greater'); 
    end if; 
end; 
/