I have been using this query to extract information from last month
SELECT *
FROM Member
WHERE DATEPART(m, date_created) = DATEPART(m, DATEADD(m, -1, getdate()))
with the end of the year approaching, will this automatically pull Dec 2012 when i run it in Jan 2013 ?
Yes. your getdate() function will give the current date when the query is run. And you are adding -1 to the month and comparing month of date_created column and the last month. But I think you should also do comparison of year. You should add two conditions month and year both.