Extract Max single upper character from table in oracle - sql

Question

I have test input table
-----------------------
RN | IDs
1 | Az
2 | Azz
3 | B
4 | C
5 | a
6 | e
--------------------
I need Output
----------
RN | IDs
4 | C
I need to get Id which is in UPPER case and single(length 1) also that ID should max in sequence. Like in this example C is the output.
Because Size is 1 , case is UPPER and MAX in sequence.
Can you please help me here.

Answer 1

The first step is identifying the ids values you want to consider. One way it to check the length and the character range:
where length(ids) = 1
and ids between 'A' and 'Z'
which makes some assumptions about your character set, or use a regular expression which also makes some assumptions:
where regexp_like(ids, '^[A-Z]$')
or preferably one which doesn't, using a class instead of a fixed range:
where regexp_like(ids, '^[[:upper:]]$')
With your data any of those give you two rows, for B and C.
You then need to find the row with the maximum ids value. You could do a self-join which is a bit wasteful; or use a subquery that calculates a ranking column and then filter on that:
select rn, ids
from (
select rn, ids, rank() over (order by ids desc) as rnk
from your_table
where regexp_like(ids, '^[[:upper:]]$')
)
where rnk = 1;
RN IDS
---------- ---
4 C
or you could use a variant of the max() function with last to do it in one step:
select max(rn) keep (dense_rank last order by IDs) as rn, max(ids)
from your_table
where regexp_like(ids, '^[[:upper:]]$');
RN MAX
---------- ---
4 C
You haven't said what should happen if there is a tie, e.g. two rn values with C. The first of those approaches will show you both - but could be modified to only show one, if you can specify which you want to see. The second will only show you one, and which is indeterminate at the moment as there is no information in the order by on how to break the tie.

Answer 2

Try this:
SELECT MAX(RN) FROM test
WHERE LENGTH(ID)=1 AND (UNICODE(ID) != UNICODE(LOWER(ID))
GROUP BY ID;

Answer 3

Use the ASCII Function
select max(RN) as MAX_ID from yourTableName t1
where length(t1.IDs)=1 and ascii(IDs) between ascii('A') and ascii('Z');

Answer 4

You can do it in this way, enjoy :)
select h.ID, h.DESC
from test_table h
where length(h.DESC) = 1
and upper(h.DESC) = h.DESC
and h.ID = (select MAX(y.ID)
from test_table y
where length(y.DESC) = 1
and upper(y.DESC) = y.DESC)

Answer 5

It's enough to filter out length(IDs)=1 firstly, and ordering with respect to decode(upper(IDs),IDs,0,1), IDs desc
select RN , IDs
from
(
select t.*,
row_number() over (order by decode(upper(IDs),IDs,0,1), IDs desc )
as rn2
from t
where length(IDs)=1
)
where rn2 = 1;
RN IDS
----- -----
4 C
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