Converting YYYYMM format to YYYY-MM-DD in SQL Server - sql

Question

I need to perform a query on a large table that has a datetime column that is indexed.
We need to query the data for a range from a month (at a minimum) to multiple months.
This query would be executed from Cognos TM1 and the input would be a period like YYYYMM. My question is - how to convert the YYYYMM input to a format that can be used to query that table (with the index being used).
Let's say if the input is
From Date: '201312'
To Date: '201312'
then, we need convert the same to 'between 01-12-2013 and 31-12-2013' in the query
Since we need this to be hooked up in Cognos TM1, so would not be able to write a procedure or declare variables (TM1 somehow does not like it).
Thanks in advance for your reply.

Answer 1

I would do something like this:
create procedure dbo.getDataForMonth
#yyyymm char(6) = null
as
--
-- use the current year/month if the year or month is invalid was omitted
--
set #yyyymm = case coalesce(#yyyymm,'')
when '' then convert(char(6),current_timestamp,112)
else #yyyymm
end
--
-- this should throw an exception if the date is invalid
--
declare #dtFrom date = convert(date,#yyyymm+'01') -- 1st of specified month
declare #dtThru date = dateadd(month,1,#dtFrom) -- 1st of next month
--
-- your Big Ugly Query Here
--
select *
from dbo.some_table t
where t.date_of_record >= #dtFrom
and t.date_of_record < #dtThru
--
-- That's about all there is to it.
--
return 0
go

Answer 2

Suppose you are getting this value of YYYYMM in a varchar variable #datefrom .
You can do something like
DECLARE #DateFrom VARCHAR(6) = '201201';
-- Append '01' to any passed string and it will get all
-- records starting from that month in that year
DECLARE #Date VARCHAR(8) = #DateFrom + '01'
-- in your query do something like
SELECT * FROM TableName WHERE DateTimeColumn >= #Date
Passing Datetime in a ansi-standard format i.e YYYYMMDD is a sargable expression and allows sql server to take advantage of indexes defined on that datetime column.
here is an article written by Rob Farley about SARGable functions in SQL Server.

Answer 3

Try this...
declare #startdate date,#endate date
select #startdate =convert(date,left('201312',4)+'-'+right('201312',2)+'-01')
select #endate= DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, #startdate) + 1, 0))
select convert(date,#startdate,102) startdate,convert(date,#endate,102) endate

Answer 4

In the datasource of your TM1 Turbo Integrator process, you can use parameters in the SQL query. E.g. you could take this SQL query:
SELECT Col1, Col2
FROM Table
WHERE Col1 = 'Green'
AND Col2 < 30
In TM1, to parameterise this, you would create two parameters e.g. P1 and P2 and put them in the query:
SELECT Col1, Col2
FROM Table
WHERE Col1 = '?P1?'
AND Col2 < ?P2?