How to get all the dates in a full calendar month - sql

Question

In a calendar control, we can see some dates from the previous month and next month also. Sample image below
(ie Apr-2016: Starts from Mar-28 and ends in May-08
Mar-2016: Starts from Apr Feb-29 and ends in Apr-10)
Here, i need to generate a list of all the dates in a calendar control for a particular year month. My week start is Monday.
Here is the tsql script i have tried so far.
DECLARE #V_DATE DATE = GETDATE()
;WITH CTE_DATE AS (
SELECT DATEADD(dd,-(DAY(#V_DATE)-1),#V_DATE) CDATE
UNION ALL
SELECT DATEADD(dd,1,CDATE)
FROM CTE_DATE
WHERE DATEADD(dd,1,CDATE) <= DATEADD(dd,-(DAY(DATEADD(mm,1,CDATE))),DATEADD(mm,1,CDATE))
)
SELECT * FROM CTE_DATE
Result Is:
2016-04-01
2016-04-02
.
.
2016-04-29
2016-04-30
It will list all the days from a inputted year month, but i need to include the
missing dates from the previous month as well as next month.
Expected result for Apr-2016
2016-03-28
2016-03-29
.
2016-04-15
.
2016-05-07
2016-05-08
Expected result for May-2016
2016-04-25
2016-04-26
.
2016-05-15
.
2016-06-04
2016-06-05
Note:- The calendar control is always showing 42 days.

Answer 1

since your week is starts on Monday,you can take referece to date 0 '1900-01-01' which is a Monday. Adding 41 days would gives you your end date
select
date_fr = dateadd(day, datediff(day, 0, '2016-05-01') / 7 * 7, 0),
date_to = dateadd(day, datediff(day, 0, '2016-05-01') / 7 * 7, 41)
the following gives you date 1900-01-01 and Monday
select convert(datetime, 0), datename(weekday, 0)

Answer 2

Have you considered creating a dates table in your database. You would have columns for dates and a column for week number. Linking to this table you could find the week number for your start and end dates, you could then re-link to the table to find the first date of your start week and the last date of your end week. This would probably be more efficient than calculations at each step each time, it is a simple link.

Answer 3

I have create done script for this. This is working as per my expectation, may be helpful for future reference. (Thanks #Squirrel for the logic).
DECLARE #V_ST_DATE DATE = GETDATE()
SET #V_ST_DATE = DATEADD(DAY,-(DAY(#V_ST_DATE)-1),#V_ST_DATE)
SET #V_ST_DATE = DATEADD(WEEK,DATEDIFF(WEEK, 0, #V_ST_DATE) ,0) +
(CASE WHEN DATEADD(WEEK,DATEDIFF(WEEK, 0, #V_ST_DATE) ,0) > #V_ST_DATE THEN -7 ELSE 0 END)
;WITH CTE_DATE AS (
SELECT #V_ST_DATE CDATE,0 TDAYS
UNION ALL
SELECT DATEADD(DAY,1,CDATE) , DATEDIFF(DAY,#V_ST_DATE, DATEADD(DAY,1,CDATE))
FROM CTE_DATE
WHERE DATEDIFF(DAY,#V_ST_DATE, DATEADD(DAY,1,CDATE)) < 42
)
SELECT * FROM CTE_DATE