Get a list of dates between two dates using a function

Question

FYI: My question is duplicate of this MySQL question, but intended for SQL Server

Is there a function to write a query that will return a list of days between two dates?

For example, lets say there is a function called ExplodeDates:

SELECT ExplodeDates('2010-01-01', '2010-01-13');

This would return a single column table with the values:

2010-01-01
2010-01-02
2010-01-03
2010-01-04
2010-01-05
2010-01-06
2010-01-07
2010-01-08
2010-01-09
2010-01-10
2010-01-11
2010-01-12
2010-01-13

Many thanks

Edit: I'm thinking that a calendar/numbers table might be able to help me here...

Update I decided to have a look at the three code answers provided, and the results of the execution - as a % of the total batch - are:

Rob Farley's answer : 18%

StingyJack's answer : 41%

KM's answer : 41%

Lower is better

I have accepted Rob Farley's answer, as it was the fastest, even though numbers table solutions (used by both KM and StingyJack in their answers) are something of a favourite of mine. Rob Farley's was two-thirds faster.

Answer 1

I'm no SQLServer expert, so I don't know if there is existing functionality there. You should use that if it's there.

If there is none, I imagine you could write a stored procedure that starts with the first date, loops through the days and adds them to some temporary table/result set until it reaches the end date.

Answer 2

A few ideas:

If you need the list dates in order to loop through them, you could have a Start Date and Day Count parameters and do a while loop whilst creating the date and using it?

Use C# CLR Stored Procedures and write the code in C#

Do this outside the database in code

Answer 3

I'm an oracle guy, but I believe MS SQL Server has support for the connect by clause:

select  sysdate + level
from    dual
connect by level <= 10 ;

The output is:

SYSDATE+LEVEL
05-SEP-09
06-SEP-09
07-SEP-09
08-SEP-09
09-SEP-09
10-SEP-09
11-SEP-09
12-SEP-09
13-SEP-09
14-SEP-09

Dual is just a 'dummy' table that comes with oracle (it contains 1 row and the word 'dummy' as the value of the single column).

Answer 4

Before you use my function, you need to set up a "helper" table, you only need to do this one time per database:

CREATE TABLE Numbers
(Number int  NOT NULL,
    CONSTRAINT PK_Numbers PRIMARY KEY CLUSTERED (Number ASC)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
DECLARE @x int
SET @x=0
WHILE @x<8000
BEGIN
    SET @x=@x+1
    INSERT INTO Numbers VALUES (@x)
END

here is the function:

CREATE FUNCTION dbo.ListDates
(
     @StartDate    char(10)  
    ,@EndDate      char(10)
)
RETURNS
@DateList table
(
    Date datetime
)
AS
BEGIN


IF ISDATE(@StartDate)!=1 OR ISDATE(@EndDate)!=1
BEGIN
    RETURN
END

INSERT INTO @DateList
        (Date)
    SELECT
        CONVERT(datetime,@StartDate)+n.Number-1
        FROM Numbers  n
        WHERE Number<=DATEDIFF(day,@StartDate,CONVERT(datetime,@EndDate)+1)


RETURN

END --Function

use this:

select * from dbo.ListDates('2010-01-01', '2010-01-13')

output:

Date
-----------------------
2010-01-01 00:00:00.000
2010-01-02 00:00:00.000
2010-01-03 00:00:00.000
2010-01-04 00:00:00.000
2010-01-05 00:00:00.000
2010-01-06 00:00:00.000
2010-01-07 00:00:00.000
2010-01-08 00:00:00.000
2010-01-09 00:00:00.000
2010-01-10 00:00:00.000
2010-01-11 00:00:00.000
2010-01-12 00:00:00.000
2010-01-13 00:00:00.000

(13 row(s) affected)

Answer 5

Would all these dates be in the database already or do you just want to know the days between the two dates? If it's the first you could use the BETWEEN or <= >= to find the dates between

EXAMPLE:

SELECT column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2

OR

SELECT column_name(s)
FROM table_name
WHERE column_name
value1 >= column_name
AND column_name =< value2

Answer 6

Try something like this:

CREATE FUNCTION dbo.ExplodeDates(@startdate datetime, @enddate datetime)
returns table as
return (
with 
 N0 as (SELECT 1 as n UNION ALL SELECT 1)
,N1 as (SELECT 1 as n FROM N0 t1, N0 t2)
,N2 as (SELECT 1 as n FROM N1 t1, N1 t2)
,N3 as (SELECT 1 as n FROM N2 t1, N2 t2)
,N4 as (SELECT 1 as n FROM N3 t1, N3 t2)
,N5 as (SELECT 1 as n FROM N4 t1, N4 t2)
,N6 as (SELECT 1 as n FROM N5 t1, N5 t2)
,nums as (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 1)) as num FROM N6)
SELECT DATEADD(day,num-1,@startdate) as thedate
FROM nums
WHERE num <= DATEDIFF(day,@startdate,@enddate) + 1
);

You then use:

SELECT *
FROM dbo.ExplodeDates('20090401','20090531') as d;

Edited (after the acceptance):

Please note... if you already have a sufficiently large nums table then you should use:

CREATE FUNCTION dbo.ExplodeDates(@startdate datetime, @enddate datetime)
returns table as
return (
SELECT DATEADD(day,num-1,@startdate) as thedate
FROM nums
WHERE num <= DATEDIFF(day,@startdate,@enddate) + 1
);

And you can create such a table using:

CREATE TABLE dbo.nums (num int PRIMARY KEY);
INSERT dbo.nums values (1);
GO
INSERT dbo.nums SELECT num + (SELECT COUNT(*) FROM nums) FROM nums
GO 20

These lines will create a table of numbers containing 1M rows... and far quicker than inserting them one by one.

You should NOT create your ExplodeDates function using a function that involves BEGIN and END, as the Query Optimizer becomes unable to simplify the query at all.

Answer 7

Definately a numbers table, though tyou may want to use Mark Redman's idea of a CLR proc/assembly if you really need the performance.

How to create the table of dates (and a super fast way to create a numbers table)

/*Gets a list of integers into a temp table (Jeff Moden's idea from SqlServerCentral.com)*/
 SELECT TOP 10950 /*30 years of days*/
        IDENTITY(INT,1,1) as N
   INTO #Numbers
   FROM Master.dbo.SysColumns sc1,
        Master.dbo.SysColumns sc2


/*Create the dates table*/
CREATE TABLE [TableOfDates](
    [fld_date] [datetime] NOT NULL,
 CONSTRAINT [PK_TableOfDates] PRIMARY KEY CLUSTERED 
(
    [fld_date] ASC
)WITH FILLFACTOR = 99 ON [PRIMARY]
) ON [PRIMARY]

/*fill the table with dates*/
DECLARE @daysFromFirstDateInTheTable int
DECLARE @firstDateInTheTable DATETIME

SET @firstDateInTheTable = '01/01/1998'
SET @daysFromFirstDateInTheTable = (SELECT (DATEDIFF(dd, @firstDateInTheTable ,GETDATE()) + 1))

INSERT INTO
      TableOfDates
SELECT 
      DATEADD(dd,nums.n - @daysFromFirstDateInTheTable, CAST(FLOOR(CAST(GETDATE() as FLOAT)) as DateTime)) as FLD_Date
FROM #Numbers nums

Now that you have a table of dates, you can use a function (NOT A PROC) like KM's to get the table of them.

CREATE FUNCTION dbo.ListDates
(
     @StartDate    DATETIME  
    ,@EndDate      DATETIME
)
RETURNS
@DateList table
(
    Date datetime
)
AS
BEGIN

/*add some validation logic of your own to make sure that the inputs are sound.Adjust the rest as needed*/

  INSERT INTO
    @DateList
  SELECT FLD_Date FROM TableOfDates (NOLOCK) WHERE FLD_Date >= @StartDate AND FLD_Date <= @EndDate
  RETURN
END

Answer 8

Perhaps if you wish to go an easier way, this should do it.

WITH date_range (calc_date) AS (
    SELECT DATEADD(DAY, DATEDIFF(DAY, 0, CURRENT_TIMESTAMP) - 6, 0)
        UNION ALL SELECT DATEADD(DAY, 1, calc_date)
            FROM date_range
            WHERE DATEADD(DAY, 1, calc_date) < CURRENT_TIMESTAMP)
SELECT calc_date
FROM date_range;

But the temporary table is a very good approach also. Perhaps shall you also consider a populated calendar table.

Answer 9

All you have to do is just change the hard coded value in the code provided below

DECLARE @firstDate datetime DECLARE @secondDate datetime DECLARE @totalDays INT SELECT @firstDate = getDate() - 30 SELECT @secondDate = getDate()

DECLARE @index INT
SELECT @index = 0
SELECT @totalDays = datediff(day, @firstDate, @secondDate)

CREATE TABLE #temp
(
     ID INT NOT NULL IDENTITY(1,1)
    ,CommonDate DATETIME NULL
)

WHILE @index < @totalDays
    BEGIN

     INSERT INTO #temp (CommonDate) VALUES  (DATEADD(Day, @index, @firstDate)) 
     SELECT @index = @index + 1
    END

SELECT CONVERT(VARCHAR(10), CommonDate, 102) as [Date Between] FROM #temp

DROP TABLE #temp