done by B4B ~~

Is here any other optimisation pontential I am missing

No, there's only one optimization you can do. Maybe there's a difference between using INNER JOIN and CROSS JOIN + WHERE, but it's not likely to be significant (at least, not in this kata).

Not an issue

Works for me: what is your error?

Every query of currency table results in the below:

PG::UndefinedTable: ERROR: relation "currency" does not exist
LINE 1: SELECT count(*) AS "count" FROM (SELECT * FROM CURRENCY) AS ...

I have the same error than CapedHero. Is there any problem?

You can use the keyword argument key to pass a function to sorted. That function is then called for each element and the result is used to determine the sort order (https://docs.python.org/3/library/functions.html#sorted) E.g. to sort a list of strings by their length you could write sorted(strings, key=len). Internally sorted will then call len(s) for each string s in strings.

As key you can pass everything that is callable with one argument and returns something sortable. To sort a list of strings case-insensitively you can write sorted(strings, key=lambda s: s.lower()) or (shorter) sorted(strings, key=str.lower). You could even create your own class MyClass with a __call__(self, arg) method and use that: sorted(sequence, key=MyClass()) (because MyClass() creates a new instance, and sort will call (pseudo-code) instance(element) which translates to MyClass.__call__(instance, element)).

In your case seq.index(element) is a function that returns the index of element in seq. If you call sorted(seq_a, key=seq_b.index), internally sorted will call seq_b.index(element) for each element and use that index for sorting.

fixed typo.
tablenames are case insensitive and i'm not creating table names in snake case.
there are no desc/asc requirements.

Thank

Thank

It's problem with server, try to do it in another time, i had the same problem when i did another kata but the next day all worked good.

I wrote name table in description in capital letters because i wanted pay attention of user to name of table, in the solution you can write name table how you want(i tried "CurRenCY" and its worked)