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

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

1. Red Boy of Differdange
Join Date
Jan 2000
Location
Chester, England.
Posts
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## 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
--
Last edited by JMac; 02-03-2004 at 01:29 PM.

2. Super Moderator
Join Date
Dec 2000
Location
Ljubljana, Slovenia
Posts
4,439
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.

3. Red Boy of Differdange
Join Date
Jan 2000
Location
Chester, England.
Posts
818
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!

Code:
```Select
Dayz
-
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
From
Dual
)
;```
PS : I have tested for few cases, not thoroughly tested...but seems ok to me.

Abhay.
Last edited by abhaysk; 02-04-2004 at 06:09 AM.

5. Member
Join Date
Jan 2004
Posts
162
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
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  /

PL/SQL procedure successfully completed.

SQL>```

6. 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.

7. Member
Join Date
Jan 2004
Posts
162
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?

Care to race?
Test by urself the above qry in my post vs PL/SQL u designed..

9. Member
Join Date
Jan 2004
Posts
162
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;
5    v_iterations PLS_INTEGER := 10 ** 5;
6    v_start_time PLS_INTEGER := 0;
7
8    TYPE tt_business_days IS TABLE OF NUMBER;
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
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
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]');
63    v_start_time := DBMS_UTILITY.get_time;
64
65    SELECT working_days (min_dte, max_dte)
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
74    v_start_time := DBMS_UTILITY.get_time;
75
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]');
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
97    FROM   table_name
98    WHERE  ROWNUM <= 100000;
99
100    DBMS_OUTPUT.put_line ('[you  (hsecs)] ' || (DBMS_UTILITY.get_time - v_start_time));
101
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
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.

10. Super Moderator
Join Date
Dec 2000
Location
Ljubljana, Slovenia
Posts
4,439
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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