# Number of working Days (Mon-Fri) between two dates?

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• 02-03-2004, 01:21 PM
JMac
Number of working Days (Mon-Fri) between two dates?
Has anyone there written - or know of - a query or function to return the number of working days between two dates?

My pseudo code would be a function accepting the two dates and returning a number of working days. Anyone have anything quicker/more elegant/ simpler?

IN (start_date, end_date) OUT (Num_days)
--
total_days := (end_date - start_date);
--
count := 1;
--
LOOP UNTIL start_date = end_date
IF TO_CHAR(start_date,'Dy') IN ('Sat','Sun')
start_date := start_date + 1
END LOOP
num_days := (total_days - count)
--
RETURN num_days
--
• 02-03-2004, 01:54 PM
jmodic
The following might be considered "more elegant" (that in fact is a matter of taste), but probably not "quicker" as it actualy selects rows from the database. Anyway:
Code:

```CREATE OR REPLACE FUNCTION working_days   (p_start_date DATE,   p_end_date DATE) RETURN NUMBER IS   v_result NUMBER; BEGIN   SELECT SUM(DECODE(DAY, '7', 0, '6', 0, 1))   INTO v_result   FROM   (SELECT TO_NUMBER(TO_CHAR(p_start_date + row_num,'D')) AS DAY   FROM     (SELECT ROWNUM-1 AS row_num FROM ALL_OBJECTS     WHERE ROWNUM < TRUNC(p_end_date+1) - TRUNC(p_start_date-1)));   RETURN v_result; END;```
Of course the day-of-the-week numbers might be different for Sat-Sun on your system, this depends on your NLS_TERRITORY setting.
• 02-04-2004, 05:23 AM
JMac
I've boiled my brain reading that one!

If I could understand how it works I might use it...

Ice cold Union pilsner for that one!
• 02-04-2004, 05:30 AM
abhaysk

Code:

```Select   Dayz       -   Nvl(Floor(Round((Dayz+Add_To_Dayz)/7,2)) * 2, 0)   Week_Days From   (   Select     Trunc(End_Date)         -     Trunc(Start_Date)         -     Decode(Substr(To_Char(Start_Date, 'DAY'), 1, 3), 'SUN', 1,                                                     'SAT', 2,                                                             0           )         -     Decode(Substr(To_Char(End_Date, 'DAY'), 1, 3), 'SUN', 2,                                                   'SAT', 1,                                                           0           )       +     1     Dayz,     Decode(Substr(To_Char(Start_Date, 'DAY'), 1, 3), 'MON', 1,                                                     'TUE', 2,                                                     'WED', 3,                                                     'THU', 4,                                                     'FRI', 5,                                                             0           ) Add_To_Dayz   From   Dual   ) ;```
PS : I have tested for few cases, not thoroughly tested...but seems ok to me.

Abhay.
• 02-04-2004, 07:09 AM
As Jurij says this does rather come down to a matter of taste.

Personally I prefer a non-looping PL/SQL only solution since in my experience that is typically the most efficient. However depending on your requirements it may be equally important that the solution is intuitive so that it can be properly understood and maintained by others - in general people appear to find looping solutions (whether by rows or in PL/SQL) to be more intuitive.
Code:

```Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production With the Partitioning, OLAP and Oracle Data Mining options JServer Release 9.2.0.4.0 - Production SQL> SET SERVEROUTPUT ON; SQL> DECLARE   2    FUNCTION named_days_between (   3      vp_min IN DATE,   4      vp_max IN DATE,   5      vp_day IN VARCHAR2)   6      RETURN NUMBER   7    IS   8    BEGIN   9      RETURN TRUNC (NEXT_DAY (vp_max, vp_day) -  10        NEXT_DAY (vp_min - 1, vp_day)) / 7;  11    END;  12     13    FUNCTION business_days_between (  14      vp_min IN DATE,  15      vp_max IN DATE)  16      RETURN NUMBER  17    IS  18    BEGIN  19      RETURN vp_max - vp_min - (  20        named_days_between (vp_min, vp_max, 'SAT') +  21        named_days_between (vp_min, vp_max, 'SUN')) + 1;  22    END;  23  BEGIN  24    DBMS_OUTPUT.PUT_LINE ('Business Days: ' ||  25      business_days_between (SYSDATE, SYSDATE + 15));  26  END;  27  / Business Days: 12 PL/SQL procedure successfully completed. SQL>```
• 02-04-2004, 08:02 AM
abhaysk
when it can be done in a qry, why go for PL/SQL .. do u think its more efficient than SQL? -- most of the times no.
• 02-04-2004, 09:19 AM
Actually I don't think generalisations like that are particularly helpful. Not that there isn't truth in it but I prefer to test all solutions and implement the most efficient one.

The example above is trivial to convert to SQL if that is your favourite flavour.
Code:

```SELECT :vp_max - :vp_min - ((           TRUNC (NEXT_DAY (:vp_max, 'SAT') - NEXT_DAY (:vp_min - 1, 'SAT')) / 7) + (           TRUNC (NEXT_DAY (:vp_max, 'SUN') - NEXT_DAY (:vp_min - 1, 'SUN')) / 7)) + 1 FROM  dual;```
Care to race?
• 02-04-2004, 09:37 AM
abhaysk
Quote:

Care to race?
Test by urself the above qry in my post vs PL/SQL u designed..
• 02-04-2004, 11:03 AM
Oh I see what you're getting at. You want to race your SQL statement against my PL/SQL function called from SQL. The cost of context switching between SQL and PL/SQL is no big secret, in fact I would say it is one of the major failings of the integration of SQL and PL/SQL. Obviously if I wanted to go fast I would not call the above function from SQL if that is what you are getting at.

Nevertheless lets test. Feel free to post any evidence you may have at any time.

I figure this logic could be used in a range of places in our application, so I will test:

1. PL/SQL direct assignment. My expression (without function call) vs. your straight SELECT FROM dual, 100,000x in PL/SQL.
2. PL/SQL calls PL/SQL function. My expression (as function call) vs. your SELECT FROM dual in a function, 100,000x in PL/SQL.
3. SQL calls PL/SQL function. My expression (as function call) vs. your SELECT FROM dual in a function, 100,000 rows in SQL.
4. Straight SQL. My SQL expression (in-line view expanded) vs your SQL expression. 100.000 rows in SQL.

I'll also use a table (called table_name, columns min_dte DATE, max_dte DATE, 1,000,000 rows).
Code:

```Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production With the Partitioning, OLAP and Oracle Data Mining options JServer Release 9.2.0.4.0 - Production SQL> SET SERVEROUTPUT ON; SQL> DECLARE   2    v_start_date DATE := SYSDATE;   3    v_end_date DATE := v_start_date + 15;   4    v_business_days NUMBER;   5    v_iterations PLS_INTEGER := 10 ** 5;   6    v_start_time PLS_INTEGER := 0;   7      8    TYPE tt_business_days IS TABLE OF NUMBER;   9    t_business_days tt_business_days := tt_business_days ();  10  BEGIN  11    DBMS_OUTPUT.PUT_LINE ('[1. PL/SQL direct assignment');  12    v_start_time := DBMS_UTILITY.get_time;  13   14    FOR i IN 1 .. v_iterations  15    LOOP  16      SELECT dayz  17            - NVL (FLOOR (ROUND ((dayz + add_to_dayz) / 7, 2)) * 2,  18                0) week_days  19      INTO  v_business_days  20      FROM  (SELECT TRUNC (v_end_date) - TRUNC (v_start_date) -  21                    DECODE (SUBSTR (TO_CHAR (v_start_date, 'DAY'), 1, 3), 'SUN', 1,'SAT', 2, 0) -  22                    DECODE (SUBSTR (TO_CHAR (v_end_date, 'DAY'), 1, 3), 'SUN', 2, 'SAT', 1, 0) + 1 dayz,  23                    DECODE (SUBSTR (TO_CHAR (v_start_date, 'DAY'), 1, 3), 'MON', 1,  24                      'TUE', 2, 'WED', 3, 'THU', 4, 'FRI', 5, 0) add_to_dayz  25              FROM  DUAL);  26    END LOOP;  27    DBMS_OUTPUT.put_line ('[you (hsecs)] ' ||  28      (DBMS_UTILITY.get_time - v_start_time));  29     30    v_start_time := DBMS_UTILITY.get_time;  31    FOR i IN 1 .. v_iterations  32    LOOP  33      v_business_days := v_end_date - v_start_date - ((  34          TRUNC (NEXT_DAY (v_end_date, 'SAT') - NEXT_DAY (v_start_date - 1, 'SAT')) / 7) + (  35          TRUNC (NEXT_DAY (v_end_date, 'SUN') - NEXT_DAY (v_start_date - 1, 'SUN')) / 7)) + 1;  36    END LOOP;  37    DBMS_OUTPUT.put_line ('[me (hsecs)] ' ||  38      (DBMS_UTILITY.get_time - v_start_time));  39     40    DBMS_OUTPUT.PUT_LINE (CHR (10) || '[2. PL/SQL calls PL/SQL function]');  41    v_start_time := DBMS_UTILITY.get_time;  42   43    FOR i IN 1 .. v_iterations  44    LOOP  45      v_business_days := working_days (v_start_date, v_end_date);  46    END LOOP;  47   48    DBMS_OUTPUT.put_line ('[you (hsecs)] ' ||  49      (DBMS_UTILITY.get_time - v_start_time));  50     51    v_start_time := DBMS_UTILITY.get_time;  52   53    FOR i IN 1 .. v_iterations  54    LOOP  55      v_business_days := business_days_between (v_start_date, v_end_date);  56    END LOOP;  57     58    DBMS_OUTPUT.put_line ('[me (hsecs)] ' ||  59      (DBMS_UTILITY.get_time - v_start_time));  60     61    DBMS_OUTPUT.PUT_LINE (CHR (10) || '[3. SQL calls PL/SQL function]');  62    t_business_days.DELETE;  63    v_start_time := DBMS_UTILITY.get_time;  64     65    SELECT working_days (min_dte, max_dte)  66    BULK COLLECT INTO t_business_days  67    FROM  table_name  68    WHERE  ROWNUM <= 100000;  69     70    DBMS_OUTPUT.put_line ('[you (hsecs)] ' ||  71      (DBMS_UTILITY.get_time - v_start_time));  72   73    t_business_days.DELETE;  74    v_start_time := DBMS_UTILITY.get_time;  75     76    SELECT business_days_between (min_dte, max_dte)  77    BULK COLLECT INTO t_business_days  78    FROM  table_name  79    WHERE  ROWNUM <= 100000;  80     81    DBMS_OUTPUT.put_line ('[me (hsecs)] ' ||  82      (DBMS_UTILITY.get_time - v_start_time));  83   84    DBMS_OUTPUT.PUT_LINE (CHR (10) || '[4. Straight SQL]');  85    t_business_days.DELETE;  86    v_start_time := DBMS_UTILITY.get_time;  87     88    SELECT TRUNC (max_dte) - TRUNC (min_dte) - DECODE (SUBSTR (TO_CHAR (  89            min_dte, 'DAY'), 1, 3), 'SUN', 1, 'SAT', 2, 0) - DECODE (  90              SUBSTR (TO_CHAR (max_dte, 'DAY'), 1, 3), 'SUN', 2, 'SAT', 1, 0) + 1 -  91          NVL (FLOOR (ROUND ((TRUNC (max_dte) - TRUNC (min_dte) - DECODE (  92            SUBSTR (TO_CHAR (min_dte, 'DAY'), 1, 3), 'SUN', 1, 'SAT', 2, 0) -  93          DECODE (SUBSTR (TO_CHAR (max_dte, 'DAY'), 1, 3), 'SUN', 2, 'SAT', 1, 0) +  94            1 + DECODE (SUBSTR (TO_CHAR (min_dte, 'DAY'), 1, 3),  95            'MON', 1, 'TUE', 2, 'WED', 3, 'THU', 4, 'FRI', 5, 0)) / 7, 2)) * 2, 0) week_days  96    BULK COLLECT INTO t_business_days  97    FROM  table_name  98    WHERE  ROWNUM <= 100000;  99    100    DBMS_OUTPUT.put_line ('[you  (hsecs)] ' || (DBMS_UTILITY.get_time - v_start_time)); 101  102    t_business_days.DELETE; 103    v_start_time := DBMS_UTILITY.get_time; 104    105    SELECT max_dte - min_dte - (( 106          TRUNC (NEXT_DAY (max_dte, 'SAT') - 107            NEXT_DAY (min_dte - 1, 'SAT')) / 7) + ( 108          TRUNC (NEXT_DAY (max_dte, 'SUN') - 109            NEXT_DAY (min_dte - 1, 'SUN')) / 7)) + 1 business_days 110    BULK COLLECT INTO t_business_days 111    FROM  table_name 112    WHERE  ROWNUM <= 100000; 113    114    DBMS_OUTPUT.put_line ('[me (hsecs)] ' || 115      (DBMS_UTILITY.get_time - v_start_time)); 116  END; 117  118  / [1. PL/SQL direct assignment] [you (hsecs)] 2904 [me (hsecs)] 525 [2. PL/SQL calls PL/SQL function] [you (hsecs)] 3043 [me (hsecs)] 652 [3. SQL calls PL/SQL function] [you (hsecs)] 3572 [me (hsecs)] 871 [4. Straight SQL] [you  (hsecs)] 699 [me (hsecs)] 200 PL/SQL procedure successfully completed. SQL>```
Looks like your 699 only beat one of my scores - that of calling PL/SQL function in PL/SQL. The cost of context switches from SQL to PL/SQL is IMHO a major limitation of the integration of PL/SQL with SQL. That's a big shame because it would be nice to encapsulate business logic in one function and use it throughout the application. Still, if I need to go really fast in SQL I have a version for that too.
• 02-04-2004, 01:00 PM
jmodic
Now that's what I call an analytical aproach! Simple, without big words, only thing that conts is hard facts (i.e. simple and meaningfull tests with easy to understand results).

Kudos!
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