Obtaining the last 36 months of data

[Jxyte]

Hi All, 

First time posting, I am looking for a slight bit of help with something I can't seem to get my head around. 

I have an Oracle Database where I need to get a count of all of the rows within the last 36 months. 

We have approximately 10 years of data and the only field which has the date field on is laid out like "BW-20200101-0001" (BW-YYYYMMDD-4 sequential numbers reset daily). I have been trying to work out how to obtain the last 36 months amount of figures. 

I've initially tried scripts like Date_Trunk('day', BW_NO) as BW_NO_TRUNK but also other scripts, is this possible at all within Qlik Sense? 

Thank you

[Jxyte]

In theory, my data looks like 

BW-20201201-0001

BW-20201201-0002

BW-20201201-0003

BW-20191201-0001

BW-20121201-0001

So I don't want to pull the record from 2012, but I would like a numerical figure about the amount of other rows. So on the above there would be a figure of 4 out of the possible 5, but there are approx 1.5-2 million rows for the whole data set, 

Thank you