On May 7, 3:52*pm, "fitzjarr...@cox.net" <orat...@msn.com> wrote:
> On May 7, 12:51*pm, sybra...@hccnet.nl wrote:
>
>
>
>
>
> > On Wed, 7 May 2008 18:45:04 +0200, "buu" <a...@a.com> wrote:
> > >question is simple... I have an date field in an table and I would liketo
> > >measure time difference (minutes or sec.) between current time and that
> > >field.
>
> > >at wich way you propose?
>
> > Assuming a non-paleolithic version of Oracle (I appreciate, you, as
> > someone asking help, can't be bothered to post it, as you assume
> > Oracle never changes), one would just subtract the two dates (the unit
> > of a date is a day), so you get the difference expressed as a days
> > fraction and feed that through the numtodsinterval function.
>
> > --
> > Sybrand Bakker
> > Senior Oracle DBA
>
> With many thanks to William Robertson for sharing this on his Oracle
> WTF site.
>
> <sarcasm>
> Oh, but it's much more fun to make things complicated:
>
> SQL> --
> SQL> -- Let's build a package of convoluted
> SQL> -- mathematical il-logic to return what
> SQL> -- would normally be the result of a
> SQL> -- simple subtraction of dates
> SQL> --
> SQL> --
> SQL> -- You simply can't beat complexity
> SQL> --
> SQL> -- Many thanks to William Robertson
> SQL> -- for bringing this exquisite example
> SQL> -- to my attention and for providing
> SQL> -- the table population code
> SQL> --
> SQL>
> SQL> CREATE PACKAGE dates_pkg
> * 2 *AS
> * 3 * * *FUNCTION julian_date
> * 4 * * * * *( date_to_convert DATE )
> * 5 * * * * *RETURN NUMBER;
> * 6
> * 7 * * *FUNCTION minutes_since_midnight
> * 8 * * * * *( timevalue DATE )
> * 9 * * * * *RETURN NUMBER;
> *10
> *11 * * *FUNCTION minutes_elapsed
> *12 * * * * *( lowdate DATE
> *13 * * * * *, highdate DATE )
> *14 * * * * *RETURN NUMBER;
> *15
> *16 *END dates_pkg;
> *17 */
>
> Package created.
>
> Elapsed: 00:00:00.01
> SQL>
> SQL> CREATE PACKAGE BODY dates_pkg
> * 2 *AS
> * 3 * * *FUNCTION julian_date
> * 4 * * * * *( date_to_convert DATE)
> * 5 * * * * *RETURN NUMBER
> * 6 * * *IS
> * 7 * * * * *varch_value VARCHAR (10);
> * 8 * * * * *num_value NUMBER (20);
> * 9 * * *BEGIN
> *10 * * * * *--
> *11 * * * * *-- First, we take a date and convert it to a dateby
> converting it
> *12 * * * * *-- to a character string using the same format wewill use
> to
> *13 * * * * *-- convert it BACK to a date again
> *14 * * * * *--
> *15 * * * * *-- Oh, then we convert it back to a character string
> *16 * * * * *--
> *17 * * * * *-- In Julian format, which is a number
> *18 * * * * *--
> *19 * * * * *SELECT TO_CHAR
> *20 * * * * * * * * ( TO_DATE(TO_CHAR(date_to_convert,'MM/DD/YYYY'),'MM/DD/
> YYYY')
> *21 * * * * * * * * , 'J')
> *22 * * * * *INTO * varch_value
> *23 * * * * *FROM * dual;
> *24
> *25 * * * * *--
> *26 * * * * *-- Okay, so we had a Julian date as a number but we changed
> it to
> *27 * * * * *-- a character string so we could go back and make it a ...
> *28 * * * * *-- NUMBER ... again
> *29 * * * * *--
> *30 * * * * *SELECT TO_NUMBER (varch_value)
> *31 * * * * *INTO * num_value
> *32 * * * * *FROM * dual;
> *33
> *34 * * * * *--
> *35 * * * * *-- So, we finally make up our mind and keep it a number and
> *36 * * * * *-- return it from the function
> *37 * * * * *--
> *38 * * * * *RETURN (num_value);
> *39 * * *END julian_date;
> *40
> *41
> *42 * * *FUNCTION minutes_since_midnight (
> *43 * * * * *timevalue DATE)
> *44 * * * * *RETURN NUMBER
> *45 * * *IS
> *46 * * * * *secs_elapsed NUMBER (20);
> *47 * * * * *mins_elapsed NUMBER (20);
> *48 * * *BEGIN
> *49 * * * * *--
> *50 * * * * *-- So now we take a date and extract the time portion of
> it,
> *51 * * * * *-- convert that BACK to a date, then convert THATto a
> string
> *52 * * * * *-- of seconds and convert THAT to a number
> *53 * * * * *--
> *54 * * * * *-- Is it me, or are we essentially driving acrosstown just
> to
> *55 * * * * *-- go next door?
> *56 * * * * *--
> *57 * * * * *SELECT TO_NUMBER
> *58 * * * * * * * * ( TO_CHAR(TO_DATE(TO_CHAR(timevalue,'HH:MI AM'),'HH:MI AM')
> *59 * * * * * * * * , 'SSSSS') )
> *60 * * * * *INTO * secs_elapsed
> *61 * * * * *FROM * dual;
> *62
> *63 * * * * *--
> *64 * * * * *-- Oooo, now we divide that total number of seconds by ...
> *65 * * * * *-- wait for it ...
> *66 * * * * *-- any second now ...
> *67 * * * * *-- 60! *Who would have thought that 60 seconds equals
> *68 * * * * *-- one minute?
> *69 * * * * *--
> *70 * * * * *SELECT (secs_elapsed / 60)
> *71 * * * * *INTO * mins_elapsed
> *72 * * * * *FROM * dual;
> *73
> *74 * * * * *--
> *75 * * * * *-- Before we rest on our laurels we return the minutes
> since midnight
> *76 * * * * *--
> *77 * * * * *RETURN (mins_elapsed);
> *78 * * *END minutes_since_midnight;
> *79
> *80
> *81 * * *FUNCTION minutes_elapsed
> *82 * * * * *( lowdate DATE
> *83 * * * * *, highdate DATE )
> *84 * * * * *RETURN NUMBER
> *85 * * *IS
> *86 * * * * *final_number NUMBER (20);
> *87 * * * * *low_julian NUMBER (20);
> *88 * * * * *high_julian NUMBER (20);
> *89 * * * * *num_days NUMBER (20);
> *90 * * * * *num_minutes NUMBER (20);
> *91 * * * * *temp_mins NUMBER (20);
> *92 * * * * *min_low NUMBER (20);
> *93 * * * * *min_high NUMBER (20);
> *94 * * *BEGIN
> *95 * * * * *--
> *96 * * * * *-- Now, why didn't we use this julian_date function in the
> *97 * * * * *-- last installment of Julian conversions?
> *98 * * * * *--
> *99 * * * * *-- Oh, yeah, because we just WROTE that wonderfulfunction
> 100 * * * * *--
> 101 * * * * *-- So, okay, we take our date values and return theJulian
> 102 * * * * *-- representations of them using all of the mathematical
> 103 * * * * *-- aerobics from earlier
> 104 * * * * *--
> 105 * * * * *-- I guess this is so much easier than simply subtracting
> 106 * * * * *-- them
> 107 * * * * *--
> 108 * * * * *SELECT julian_date (lowdate)
> 109 * * * * *INTO * low_julian
> 110 * * * * *FROM * dual;
> 111
> 112 * * * * *SELECT julian_date (highdate)
> 113 * * * * *INTO * high_julian
> 114 * * * * *FROM * dual;
> 115
> 116 * * * * *--
> 117 * * * * *-- Woo-hoo! Higher math time! *Subtract the Julian dates
> 118 * * * * *-- and get the number of days
> 119 * * * * *--
> 120 * * * * *-- Isn't that what we'd get if we just subtracted the
> 121 * * * * *-- submitted dates as-is?
> 122 * * * * *--
> 123 * * * * *-- Of course it is
> 124 * * * * *--
> 125 * * * * *SELECT (high_julian - low_julian)
> 126 * * * * *INTO * num_days
> 127 * * * * *FROM * dual;
> 128
> 129 * * * * *--
> 130 * * * * *-- Now we calculate the total minutes elapsed
> 131 * * * * *-- using our values generated by our extreme
> 132 * * * * *-- gyrations
> 133 * * * * *--
> 134 * * * * *-- I'm out of breath just thinking about all of this work
> 135 * * * * *--
> 136 * * * * *SELECT (num_days * 1440)
> 137 * * * * *INTO * num_minutes
> 138 * * * * *FROM * dual;
> 139
> 140 * * * * *--
> 141 * * * * *-- And now we put those other mathematical moves
> 142 * * * * *-- to use
> 143 * * * * *--
> 144 * * * * *-- Tell me again why we think we're smarter than
> 145 * * * * *-- the average bear?
> 146 * * * * *--
> 147 * * * * *SELECT minutes_since_midnight (lowdate)
> 148 * * * * *INTO * min_low
> 149 * * * * *FROM * dual;
> 150
> 151 * * * * *SELECT minutes_since_midnight (highdate)
> 152 * * * * *INTO * min_high
> 153 * * * * *FROM * dual;
> 154
> 155 * * * * *--
> 156 * * * * *-- Now this is disgusting
> 157 * * * * *--
> 158 * * * * *-- Using a TEMP variable to aid in simple mathematical
> 159 * * * * *-- processing
> 160 * * * * *--
> 161 * * * * *SELECT (min_high - min_low)
> 162 * * * * *INTO * temp_mins
> 163 * * * * *FROM * dual;
> 164
> 165 * * * * *--
> 166 * * * * *-- And this is better than:
> 167 * * * * *-- select (end_date - start_date)*1440 because?
> 168 * * * * *--
> 169 * * * * *SELECT (num_minutes + temp_mins)
> 170 * * * * *INTO * final_number
> 171 * * * * *FROM * dual;
> 172
> 173 * * * * *RETURN (final_number);
> 174
> 175 * * *END minutes_elapsed;
> 176 *END dates_pkg;
> 177 */
>
> Package body created.
>
> Elapsed: 00:00:00.04
> SQL>
> SQL> --
> SQL> -- This is more fun with a test table
> SQL> --
> SQL>
> SQL> create table date_tst ( start_dt date, end_dt date);
>
> Table created.
>
> Elapsed: 00:00:00.01
> SQL>
> SQL> insert into date_tst
> * 2 *select date '2006-12-25' + dbms_random.value(1,365)
> * 3 * * * , date '2007-12-25' + dbms_random.value(1,365)
> * 4 *FROM * dual connect by level <= 4000;
>
> 4000 rows created.
>
> Elapsed: 00:00:00.15
>
> SQL>
> SQL> commit;
>
> Commit complete.
>
> Elapsed: 00:00:00.01
> SQL>
> SQL> --
> SQL> --
> SQL> -- Let's execute this mess
> SQL> --
> SQL> --
> SQL>
> SQL> set timing on autotrace traceonly
> SQL>
> SQL> select dates_pkg.minutes_elapsed(start_dt, end_dt) from date_tst;
>
> 4000 rows selected.
>
> Elapsed: 00:00:03.01
>
> Execution Plan
> ----------------------------------------------------------
> Plan hash value: 2261420801
>
> ---------------------------------------------------------------------------*---
> | Id *| Operation * * * * | Name * * | Rows *| Bytes | Cost (%CPU)|
> Time * * |
> ---------------------------------------------------------------------------*---
> | * 0 | SELECT STATEMENT *| * * * * *| *4000 | 72000 | ** 5 * (0)|
> 00:00:01 |
> | * 1 | *TABLE ACCESS FULL| DATE_TST | *4000 | 72000 | * * 5 *(0)|
> 00:00:01 |
> ---------------------------------------------------------------------------*---
>
> Note
> -----
> * *- dynamic sampling used for this statement
>
> Statistics
> ----------------------------------------------------------
> * * * 64014 *recursive calls
> * * * * * 0 *db block gets
> * * * * 300 *consistent gets
> * * * * * 0 *physical reads
> * * * * * 0 *redo size
> * * * 38634 *bytes sent via SQL*Net to client
> * * * *2108 *bytes received via SQL*Net from client
> * * * * 268 *SQL*Net roundtrips to/from client
> * * * * * 0 *sorts (memory)
> * * * * * 0 *sorts (disk)
> * * * *4000 *rows processed
>
> SQL>
> SQL> select (end_dt - start_dt)*1440 from date_tst;
>
> 4000 rows selected.
>
> Elapsed: 00:00:00.21
>
> Execution Plan
> ----------------------------------------------------------
> Plan hash value: 2261420801
>
> ---------------------------------------------------------------------------*---
> | Id *| Operation * * * * | Name * * | Rows *| Bytes | Cost (%CPU)|
> Time * * |
> ---------------------------------------------------------------------------*---
> | * 0 | SELECT STATEMENT *| * * * * *| *4000 | 72000 | ** 5 * (0)|
> 00:00:01 |
> | * 1 | *TABLE ACCESS FULL| DATE_TST | *4000 | 72000 | * * 5 *(0)|
> 00:00:01 |
> ---------------------------------------------------------------------------*---
>
> Note
> -----
> * *- dynamic sampling used for this statement
>
> Statistics
> ----------------------------------------------------------
> * * * * * 4 *recursive calls
> * * * * * 0 *db block gets
> * * * * 300 *consistent gets
> * * * * * 0 *physical reads
> * * * * * 0 *redo size
> * * *103258 *bytes sent via SQL*Net to client
> * * * *2108 *bytes received via SQL*Net from client
> * * * * 268 *SQL*Net roundtrips to/from client
> * * * * * 0 *sorts
> ...
>
> read more »- Hide quoted text -
>
> - Show quoted text -

I think since the difference between two timestamps is a timestamp I
would go this route:

UT1 > l
1 select fld5, to_timestamp(sysdate) - fld5,
2 extract(day from to_timestamp(sysdate) - fld5 ) as Days,
3 extract(hour from to_timestamp(sysdate) - fld5 ) as Hours
4* from marktest
UT1 > /

FLD5
---------------------------------------------------------------------------
TO_TIMESTAMP(SYSDATE)-FLD5
---------------------------------------------------------------------------
DAYS HOURS
---------- ----------
23-OCT-07 01.21.09.367316 PM
+000000196 10:38:50.632684
196 10

23-OCT-07 01.21.17.584899 PM
+000000196 10:38:42.415101
196 10

20-FEB-08 11.18.24.606839 AM
+000000076 12:41:35.393161
76 12

The difference is Days, hours, minutes, seconds, and fractions there
of so it is human readable as is. This can be useful. If you need
the components you can extract them or as Sybrand said look at the
interval functions and also datatypes.

HTH -- Mark D Powell --