Generate Dates Between Date Ranges

Generate Dates between date ranges

Easy on SQL 2005+; easier if you have a numbers or tally table. I faked it below:

DECLARE @StartDate DATE = '20110901'
  , @EndDate DATE = '20111001'

SELECT  DATEADD(DAY, nbr - 1, @StartDate)
FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY c.object_id ) AS nbr
          FROM      sys.columns c
        ) nbrs
WHERE   nbr - 1 <= DATEDIFF(DAY, @StartDate, @EndDate)

If you have a tally table, replace the subquery with the table. No recursion.

EDIT: Since folks seem to have questions about the tally table, let me rewrite this using a zero-based tally table. First, here's some code to create and populate a table.

CREATE TABLE [dbo].[nbrs](
    [nbr] [INT] NOT NULL
) ON [PRIMARY]
GO


CREATE UNIQUE CLUSTERED INDEX [clidx] ON [dbo].[nbrs]
(
    [nbr] ASC
)
GO

INSERT INTO dbo.nbrs (nbr)
SELECT nbr-1
FROM ( SELECT    ROW_NUMBER() OVER ( ORDER BY c.object_id ) AS nbr
          FROM      sys.columns c
        ) nbrs
GO

Now, that you have the numbers table as a permanent object in your database, you can reuse it for the query INSTEAD of the subquery. The query has also been edited to use a zero-based calculation.

DECLARE @StartDate DATE = '20110901'
      , @EndDate DATE = '20111001'

SELECT  DATEADD(DAY, nbr, @DateStart)
FROM    nbrs
WHERE   nbr <= DATEDIFF(DAY, @DateStart, @DateEnd)

Performant, and no recursion.

Get all dates between two dates in SQL Server

My first suggestion would be use your calendar table, if you don't have one, then create one. They are very useful. Your query is then as simple as:

DECLARE @MinDate DATE = '20140101',
        @MaxDate DATE = '20140106';

SELECT  Date
FROM    dbo.Calendar
WHERE   Date >= @MinDate
AND     Date < @MaxDate;

If you don't want to, or can't create a calendar table you can still do this on the fly without a recursive CTE:

DECLARE @MinDate DATE = '20140101',
        @MaxDate DATE = '20140106';

SELECT  TOP (DATEDIFF(DAY, @MinDate, @MaxDate) + 1)
        Date = DATEADD(DAY, ROW_NUMBER() OVER(ORDER BY a.object_id) - 1, @MinDate)
FROM    sys.all_objects a
        CROSS JOIN sys.all_objects b;

For further reading on this see:

• Generate a set or sequence without loops – part 1
• Generate a set or sequence without loops – part 2
• Generate a set or sequence without loops – part 3

With regard to then using this sequence of dates in a cursor, I would really recommend you find another way. There is usually a set based alternative that will perform much better.

So with your data:

  date   | it_cd | qty 
24-04-14 |  i-1  | 10 
26-04-14 |  i-1  | 20

To get the quantity on 28-04-2014 (which I gather is your requirement), you don't actually need any of the above, you can simply use:

SELECT  TOP 1 date, it_cd, qty 
FROM    T
WHERE   it_cd = 'i-1'
AND     Date <= '20140428'
ORDER BY Date DESC;

If you don't want it for a particular item:

SELECT  date, it_cd, qty 
FROM    (   SELECT  date, 
                    it_cd, 
                    qty, 
                    RowNumber = ROW_NUMBER() OVER(PARTITION BY ic_id 
                                                    ORDER BY date DESC)
            FROM    T
            WHERE   Date  <= '20140428'
        ) T
WHERE   RowNumber = 1;

Python generating a list of dates between two dates

You can use pandas.date_range() for this:

import pandas
pandas.date_range(sdate,edate-timedelta(days=1),freq='d')

---

DatetimeIndex(['2019-03-22', '2019-03-23', '2019-03-24', '2019-03-25',
           '2019-03-26', '2019-03-27', '2019-03-28', '2019-03-29',
           '2019-03-30', '2019-03-31', '2019-04-01', '2019-04-02',
           '2019-04-03', '2019-04-04', '2019-04-05', '2019-04-06',
           '2019-04-07', '2019-04-08'],
          dtype='datetime64[ns]', freq='D')

Creating a range of dates in Python

Marginally better...

base = datetime.datetime.today()
date_list = [base - datetime.timedelta(days=x) for x in range(numdays)]

How to Auto generate dates between date range using SQL Query?

Here is how to accomplish this by using a tally table to create a calendar table:

declare @source table
(
    user_id int not null primary key clustered,
    from_date date not null,
    to_date date not null
);

insert into @source
values
(1, '02/20/2019', '02/23/2019'),
(2, '02/22/2019', '02/28/2019'),
(3, '03/01/2019', '03/05/2019');

with
rows as
(
    select top 1000
    n = 1
    from sys.messages
),
tally as
(
    select n = row_number() over(order by (select null)) - 1
    from rows
),
calendar as
(
    select
    date = dateadd(dd, n, (select min(from_date) from @source))
    from tally
)
select
s.user_id,
c.date
from @source s
cross join calendar c
where c.date between s.from_date and s.to_date;

Result set:

generate days from date range

This solution uses no loops, procedures, or temp tables. The subquery generates dates for the last 10,000 days, and could be extended to go as far back or forward as you wish.

select a.Date 
from (
    select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a) + (1000 * d.a) ) DAY as Date
    from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as d
) a
where a.Date between '2010-01-20' and '2010-01-24' 

Output:

Date
----------
2010-01-24
2010-01-23
2010-01-22
2010-01-21
2010-01-20

Notes on Performance

Testing it out here, the performance is surprisingly good: the above query takes 0.0009 sec.

If we extend the subquery to generate approx. 100,000 numbers (and thus about 274 years worth of dates), it runs in 0.0458 sec.

Incidentally, this is a very portable technique that works with most databases with minor adjustments.

SQL Fiddle example returning 1,000 days

Javascript - get array of dates between 2 dates

function (startDate, endDate, addFn, interval) {

 addFn = addFn || Date.prototype.addDays;
 interval = interval || 1;

 var retVal = [];
 var current = new Date(startDate);

 while (current <= endDate) {
  retVal.push(new Date(current));
  current = addFn.call(current, interval);
 }

 return retVal;

}

Create an array or List of all dates between two dates

LINQ:

Enumerable.Range(0, 1 + end.Subtract(start).Days)
          .Select(offset => start.AddDays(offset))
          .ToArray(); 

For loop:

var dates = new List();

for (var dt = start; dt <= end; dt = dt.AddDays(1))
{
   dates.Add(dt);
}

EDIT:
As for padding values with defaults in a time-series, you could enumerate all the dates in the full date-range, and pick the value for a date directly from the series if it exists, or the default otherwise. For example:

var paddedSeries = fullDates.ToDictionary(date => date, date => timeSeries.ContainsDate(date) 
                                               ? timeSeries[date] : defaultValue);

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