Get a list of dates between two dates using a function

Question

My question is similar to this MySQL question, but intended for SQL Server:

Is there a function or a query that will return a list of days between two dates? For exa

Answer 1

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 2

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 3

This query works on Microsoft SQL Server.

select distinct format( cast('2010-01-01' as datetime) + ( a.v / 10 ), 'yyyy-MM-dd' ) as aDate
       from (
             SELECT ones.n + 10 * tens.n + 100 * hundreds.n + 1000 * thousands.n as v
             FROM (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) ones(n),
                    (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) tens(n),
                    (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) hundreds(n),
                  (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) thousands(n)
       ) a
       where format( cast('2010-01-01' as datetime) + ( a.v / 10 ), 'yyyy-MM-dd' ) < cast('2010-01-13' as datetime)
       order by aDate asc;

Now let's look at how it works.

The inner query merely returns a list of integers from 0 to 9999. It will give us a range of 10,000 values for calculating dates. You can get more dates by adding rows for ten_thousands and hundred_thousands and so forth.

SELECT ones.n + 10 * tens.n + 100 * hundreds.n + 1000 * thousands.n as v
         FROM (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) ones(n),
                (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) tens(n),
                (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) hundreds(n),
              (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) thousands(n)
   ) a;

This part converts the string to a date and adds a number to it from the inner query.

cast('2010-01-01' as datetime) + ( a.v / 10 )

Then we convert the result into the format you want. This is also the column name!

format( cast('2010-01-01' as datetime) + ( a.v / 10 ), 'yyyy-MM-dd' )

Next we extract only the distinct values and give the column name an alias of aDate.

distinct format( cast('2010-01-01' as datetime) + ( a.v / 10 ), 'yyyy-MM-dd' ) as aDate

We use the where clause to filter in only dates within the range you want. Notice that we use the column name here since SQL Server does not accept the column alias, aDate, within the where clause.

where format( cast('2010-01-01' as datetime) + ( a.v / 10 ), 'yyyy-MM-dd' ) < cast('2010-01-13' as datetime)

Lastly, we sort the results.

   order by aDate asc;