Question

I have a rather confusing SQLite query that I can’t seem to quite wrap my brain around.

I have the following four tables:

Table “S”

sID (string/guid)  | sNum (integer)
-----------------------------------
aaa-aaa                   1
bbb-bbb                   2
ccc-ccc                   3
ddd-ddd                   4
eee-eee                   5
fff-fff                   6
ggg-ggg                   7

Table “T”

tID (string/guid) | ... other stuff
-----------------------------------
000
www
xxx
yyy
zzz

Table “S2TMap”

sID    |    tID
-------------------
aaa-aaa    000
bbb-bbb    000
ccc-ccc    xxx
ddd-ddd    yyy
eee-eee    www
fff-fff    000
ggg-ggg    000

Table “temp”

oldID (string/guid) | newID (string/guid)
------------------------------------------
   dont care          fff-fff
   dont care          ggg-ggg
   dont care          zzz

What I need is to be able to get the MAX() sNum that exists in a specified “t” if the sID doesn’t exist in the temp.NewID table.

For example, given the T ‘000’, ‘000’ has S ‘aaa-aaa’, ‘bbb-bbb’, ‘fff-fff’, and ‘ggg-ggg’ mapped to it. However, both ‘fff-fff’ and ‘ggg-ggg’ exist in the TEMP table, which means I need to only look at ‘aaa-aaa’ and ‘bbb-bbb’. Thus, the statement would return “2”.

---

How would I go about doing this?

I was thinking something along the lines of the following for selecting s that don’t exist in the “temp” table, but I’m not sure how to get the max of the seat and only do it based on a specific ‘t’

SELECT s.sID, s.sNum FROM s WHERE NOT EXISTS ( SELECT newID from temp where tmp.newID = s.sID)

Thanks!

Answer 1

Give this a try:

select max(s.sNum) result from s2tmap st
join s on st.sId = s.sId
where st.tId = '000' and not exists (
  select * from temp
  where temp.newId = st.sId)

Here is the fiddle to play with.

Another option, probably less efficient would be:

select max(s.sNum) result from s2tmap st
join s on st.sId = s.sId
where st.tId = '000' and st.sId not in (
  select newId from temp)