More database trouble.

SQLSTATE should really be a string. Those codes can have leading zeros.
If people get comfortable typing them unadorned as 12345, then a 01234
will strip the leading zero, which I think is not valid (the codes need
to be exactly 5 characters long). You'd have to pay attention and quote
it as '|01234|, and even then it's a symbol instead of a number even
though it looks like a number. Or we could have '|12345| also be a
symbol, but that's weird because to humans it's a number.

The only sensible solution is always string: "12345", "01234", "08P01".

MariaDB has errors like this:

Error Code      1004
Error           ER_CANT_CREATE_FILE
SQLSTATE        HY000
Description     Can't create file '%s' (errno: %d)

so a separate proprietary error code and SQLSTATE code.

This would look reasonable:

(make-foreign-status
  'number   1004
  'symbol   ER_CANT_CREATE_FILE
  'sqlstate "HY000"
  'message  "Can't create file '...' (errno: ...)")