SQL - Insert all dates within range from table into another - sql

Question

I'm looking to populate a table with dates, based upon values contained within another.
Source : tblA
dtFrom dtTo
2019-01-01 2019-01-03
2019-02-01 2019-02-02
2019-03-01 2019-03-01
Destination : tblB
sDate
2019-01-01
2019-01-02
2019-01-03
2019-02-01
2019-02-02
2019-03-01
SQL Server 2014. As always, thanks in advance :-)

Answer 1

You can use a recursive CTE:
with dates as (
select dtfrom as dt, dtto
from tblA
union all
select dateadd(day, 1, dt), dtto
from dates
where dt < dtto
)
insert tblB (sDate)
select distinct dt
from dates;
The select distinct is only necessary to handle overlapping periods. If you know there are no overlaps, then don't use it.

Answer 2

You can use union to combine values from both columns into one rowset:
insert tblB
(sDate)
select distinct dt
from (
select dtFrom as dt
from tblA
union all
select dtTo
from tblA
) s

Answer 3

Use the always handy Calendar Table, which is a table that holds 1 row for each day, for all days between specific years. You can add additional columns like IsBusinessDay or WorkingStartHour / WorkingEndHour to make your date queries much easier.
-- Create Calendar Table
DECLARE #StartDate DATE = '2000-01-01'
DECLARE #EndDate DATE = '2050-01-01'
SET DATEFIRST 1 -- 1: Monday, 7: Sunday
CREATE TABLE CalendarTable (
Date DATE PRIMARY KEY,
IsWorkingDay BIT
-- Other columns you might need
)
;WITH RecursiveCTE AS
(
SELECT
Date = #StartDate
UNION ALL
SELECT
Date = DATEADD(DAY, 1, R.Date)
FROM
RecursiveCTE AS R
WHERE
DATEADD(DAY, 1, R.Date) <= #EndDate
)
INSERT INTO CalendarTable (
Date,
IsWorkingDay)
SELECT
Date = R.Date,
IsWorkingDay = CASE WHEN DATEPART(WEEKDAY, R.Date) BETWEEN 1 AND 5 THEN 1 ELSE 0 END
FROM
RecursiveCTE AS R
OPTION
(MAXRECURSION 0)
Now with your calendar table, just join with a BETWEEN and INSERT to your destination table. You can use DISTINCT to make sure dates don't repeat:
INSERT INTO tblB (
sDate)
SELECT DISTINCT
sDate = C.Date
FROM
tlbA AS A
INNER JOIN CalendarTable AS C ON C.Date BETWEEN A.dtFrom AND A.dtTo
Let's say for example that you only want to insert records that are working days (monday to friday). You just need to filter the calendar table and done. You can add whichever logic you want on your table and just filter it when using, without repeating complex datetime logics.
INSERT INTO tblB (
sDate)
SELECT DISTINCT
sDate = C.Date
FROM
tlbA AS A
INNER JOIN CalendarTable AS C ON C.Date BETWEEN A.dtFrom AND A.dtTo
WHERE
C.IsWorkingDay = 1

Answer 4

With a Calendar you can inner join on the ranges to produce an Insert statement.
DECLARE #StartDate DATETIME = (SELECT MIN(dtFrom) FROM tblA)
DECLARE #EndDate DATETIME = (SELECT MAX(dtTo) FROM tblB)
;WITH Calendar as
(
SELECT CalendarDate = #StartDate, CalendarYear = DATEPART(YEAR, #StartDate), CalendarMonth = DATEPART(MONTH, #StartDate)
UNION ALL
SELECT CalendarDate = DATEADD(MONTH, 1, CalendarDate), CalendarYear = DATEPART(YEAR, CalendarDate), CalendarMonth = DATEPART(MONTH, CalendarDate)
FROM Calendar WHERE DATEADD (MONTH, 1, CalendarDate) <= #EndDate
)
INSERT INTO tblB
SELECT DISTINCT
C.CalendarDate
FROM
Calendar C
INNER JOIN tblA A ON C.CalendarDate BETWEEN A.dtFrom AND A.dtTo

Answer 5

You can achieve this result by using the below queries.
Steps 1 - Create a Custom Function which will take date range as a parameter and will return date series.
CREATE FUNCTION [dbo].[GenerateDateRange]
(#StartDate AS DATE,
#EndDate AS DATE,
#Interval AS INT
)
RETURNS #Dates TABLE(DateValue DATE)
AS
BEGIN
DECLARE #CUR_DATE DATE
SET #CUR_DATE = #StartDate
WHILE #CUR_DATE <= #EndDate BEGIN
INSERT INTO #Dates VALUES(#CUR_DATE)
SET #CUR_DATE = DATEADD(DAY, #Interval, #CUR_DATE)
END
RETURN;
END;
Step 2 - Join this custom function with your table tblA and insert the record in tblb as needed
insert tblb
select b.* from tblA a cross apply dbo.GenerateDateRange(a.dtFrom, a.dtTo, 1) b