I don't think the accepted solution is very index friendly
I use the following lines instead
select * from dbtable where the_date >= convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120) and the_date <= dateadd(ms, -3, convert(varchar(10),DATEADD(m, 0, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120));
Or simply (this is the best).
select * from dbtable where the_date >= convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120) and the_date < SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
Some help
-- Get the first of last month
SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
-- Get the first of current month
SELECT convert(varchar(10),DATEADD(m, -1, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120);
--Get the last of last month except the last 3milli seconds. (3miliseconds being used as SQL express otherwise round it up to the full second (SERIUSLY MS)
SELECT dateadd(ms, -3, convert(varchar(10),DATEADD(m, 0, dateadd(d, - datepart(dd, GETDATE())+1, GETDATE())),120));