SQL Query to categorize results of separate query - sql

Question

I am trying to run a query on the results of a separate query to update the Route_Type column for each record based on unique Route_Code and Delivery_Day. For each distinct Route_Code from the select query, the Route_Type should be updated based on the following logic:
if there are no records for a specific Route_Code where Delivery_Day = 'Mon' then Route_Type should update to 'A'
if there are no records for a specific Route_Code where Delivery_Day = 'Sat' then Route_Type should update to 'B'
If there are no records for a specific Route_Code where Delivery_Day = 'Mon' OR 'Sat' then Route_Type should be 'TBD'
Else Route_Type = 'Both.'
Data:
Record Route_Code Delivery_Day Route_Type
1 112 Mon
2 112 Thur
3 112 Sat
4 112 Sun
5 113 Tue
6 113 Fri
7 113 Sat
8 113 Sun
9 113 Wed
Select Query:
Select Distinct Route_Code
From Deliveries;
Results:
Route_Code
1 112
2 113
The query should return all unique Route_Code and the calculated Route_Type for each, shown below...
Desired Query Result:
Route_Code Route_Type
1 112 Both
2 113 A
As a follow-up, I want all Route_Codes that have fewer than 1 month of records to display 'TBD.' The logic I have so far is
When
Max(sum(case when Delivery_Day= 'Mon' then 1 else 0 end),
sum(case when Delivery_Day= 'Tue' then 1 else 0 end),
sum(case when Delivery_Day= 'Wed' then 1 else 0 end),
sum(case when Delivery_Day= 'Thu' then 1 else 0 end),
sum(case when Delivery_Day= 'Fri' then 1 else 0 end),
sum(case when Delivery_Day= 'Sat' then 1 else 0 end),
sum(case when Delivery_Day= 'Sun' then 1 else 0 end)
Then 'TBD'
I realize that the native Max() function handles only single arguments, and am wondering where to go from here.

Answer 1

This sounds like aggregation. I find your logic a bit hard to follow. If I understand correctly, "B" has a Monday delivery and "A" has a Saturday. The logic looks like this:
select route_code,
(case when sum(case when Delivery_Day = 'Mon' then 1 else 0 end) > 0 and
sum(case when Delivery_Day = 'Sat' then 1 else 0 end) > 0
then 'Both'
when sum(case when Delivery_Day = 'Mon' then 1 else 0 end) > 0
then 'B'
when sum(case when Delivery_Day = 'Sat' then 1 else 0 end) > 0
then 'A'
else 'TBD'
end) as route_type
from delivies
group by route_code