sql script: Calculating Days

 1 --日曆(sql server 2005)
 2 
 3 CREATE TABLE T1 (ID INTEGER)
 4 INSERT INTO T1 VALUES (1)
 5 ----
 6 with x(dy,dm,mth,dw,wk)
 7 as(
 8 select dy,
 9        day(dy) dm,
10         datepart(m,dy) mth,
11        datepart(dw,dy) dw,       
12         case when datepart(dw,dy)=1
13         then datepart(ww,dy)-1
14         else datepart(ww,dy)
15         end wk
16 from(
17 select dateadd(day,-day(getdate())+1,getdate()) dy
18 from t1
19 ) x
20 union all 
21 select dateadd(d,1,dy),day(dateadd(d,1,dy)),mth,
22     datepart(dw,dateadd(d,1,dy)),
23     case when datepart(dw,dateadd(d,1,dy))=1
24     then datepart(wk,dateadd(d,1,dy))-1
25     else datepart(wk,dateadd(d,1,dy))
26    end
27 from x
28 where datepart(m,dateadd(d,1,dy))=mth
29 )
30 select max(case dw when 2 then dm end) as Mo,
31        max(case dw when 3 then dm end) as Tu,
32        max(case dw when 4 then dm end) as We,
33        max(case dw when 5 then dm end) as Th,
34        max(case dw when 6 then dm end) as Fr,
35        max(case dw when 7 then dm end) as Sa,
36        max(case dw when 1 then dm end) as Su
37 from x
38 group by wk
39 order by wk
40 
41 ---
42 select dy,
43         day(dy) dm,
44         datepart(m,dy) mth,
45         datepart(dw,dy) dw,
46         case when datepart(dw,dy)=1
47         then datepart(ww,dy)-1
48         else datepart(ww,dy)
49         end wk
50    from(
51     select dateadd(day,-day(getdate())+1,getdate()) dy
52 from t1
53 ) x
54 go
55 
56 --第幾周
57 with x(dy,dm,mth,dw,wk)
58 as(
59 select dy,
60              day(dy) dm,
61         datepart(m,dy) mth,
62         datepart(dw,dy) dw,
63         case when datepart(dw,dy)=1
64         then datepart(ww,dy)-1
65         else datepart(ww,dy)
66         end wk
67 from(
68 select dateadd(day,-day(getdate())+1,getdate()) dy
69 from t1
70 ) x 
71 union all 
72 select dateadd(d,1,dy), day(dateadd(d,1,dy)),mth,
73         datepart(dw,dateadd(d,1,dy)),
74       case when datepart(dw,dateadd(d,1,dy))=1
75          then datepart(wk,dateadd(d,1,dy))-1
76          else datepart(wk,dateadd(d,1,dy))
77       end
78 from x
79 where datepart(m,dateadd(d,1,dy))=mth
80 )
81 select * from x

 1 ---
 2 CREATE FUNCTION [dbo].[f_week_days_in_period] (@start_date datetime, @end_date datetime)
 3 RETURNS INT
 4 AS
 5 BEGIN
 6       
 7       -- If the start date is a weekend, move it foward to the next weekday
 8       WHILE datepart(weekday, @start_date) in (1,7) -- Sunday, Saturday
 9       BEGIN
10           SET @start_date = dateadd(d,1,@start_date)
11       END
12       
13       -- If the end date is a weekend, move it back to the last weekday
14       WHILE datepart(weekday, @end_date) in (1,7) -- Sunday, Saturday
15       BEGIN
16           SET @end_date = dateadd(d,-1,@end_date)
17       END
18       
19       -- Weekdays are total days in perion minus weekends. (2 days per weekend)
20       -- Extra weekend days were trimmed off the period above.
21       -- I am adding an extra day to the total to make it inclusive. 
22       --     i.e. 1/1/2008 to 1/1/2008 is one day because it includes the 1st
23       RETURN (datediff(d,@start_date,@end_date) + 1) - (datediff(ww,@start_date,@end_date) * 2)
24   
25   END
26 
27 ---
28 select dbo.f_week_days_in_period('2013-02-01','2013-02-28')