Convert datetime from substring T-SQL

Question

I have been trying to figure out how to convert a select result that returns 2 digits and then I want to convert it into year so then I can grab the max() value of that year.

My table:

ins_order
------------------------
RSN  |  ordered
---------------
1    |  A04-01
2    |  A12-02
3    |  A98-01
4    |  B00-10
2    |  B10-02
3    |  C97-01
4    |  C03-10

and so on...

My select state looks like this:

select 
    max(substring(orderid, patindex('%[0-9]-%', orderid) - 1, 2)) as year
from 
    ins.insorders
where 
    orderid is not null
group by 
    substring(orderid, 0, patindex('%[0-9]%', orderid))
order by 
    year

This will return:

year
---------
98           
10
97

but when I use max it returns the highest number for each letter, but before getting the highest number I need to convert this 2 numbers into year format so it can understand that 17 is actually the highest because we are in 2017.

Answer 1

As Sean Lange said in his comment, you are going to have to convert your substring() to a meaningful value before trying to use it in a meaningful way.

select 
    Ltr = substring(orderid, 0, patindex('%[0-9]%', orderid))
  , Year = max(case when convert(int,substring(orderid, patindex('%[0-9]-%', orderid) - 1, 2)) < 50
  then convert(int,'20'+substring(orderid, patindex('%[0-9]-%', orderid) - 1, 2))
  else convert(int,'19'+substring(orderid, patindex('%[0-9]-%', orderid) - 1, 2))
  end)
from ins_orders
group by substring(orderid, 0, patindex('%[0-9]%', orderid))
order by year desc

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returns:

+-----+------+
| Ltr | Year |
+-----+------+
| A   | 2012 |
| B   | 2010 |
| C   | 2003 |
+-----+------+