RDB$DB_KEY and Delphi

Question:

I have put together a small delphi project that just selects rdb$db_key from a table and displays the results in a grid, but the db_key field is not displayed properly instead of '000000B600000002', what is displayed as a non readable character. From what I can gather, Delphi returns it as a variant and although I store it in a variable as a variant, I cannot then use it to run another query to locate the same record.

Answer:

One solution is to cast the db_key to the OCTETS character set which then effectively returns a UUID. You can then convert the UUID to a string:

select uuid_to_char(
  cast (rdb$db_key as char(16) character set octets)
  )
FROM EMPLOYEE
rows 1;

UUID_TO_CHAR
====================================
83000000-0100-0000-0000-000000000000

You can then retrieve the row using the following:

 EMP_NO LAST_NAME
======= ====================
      2 Nelson

It's a bit awkward but it works. In this case we are using the db_key to allow persistence in a web server. The string gets passed to the browser in a url and then when the browser wants that row it sends back the db_key in string format. That format is then easily manipulated by stored procedures.