在SQL Server中将YYYYMM格式转换为YYYY-MM-DD

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

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 ie 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 2

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 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. Eg 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 eg P1 and P2 and put them in the query:

SELECT Col1, Col2
FROM Table
WHERE Col1 = '?P1?'
AND Col2 < ?P2?