Table: euro_convergence
Columns: currency
code
entry_erm_ii
central_rate
official_target_date

Question: What type of currency has a code of SEK?
SQL: SELECT "currency" FROM euro_convergence WHERE "code" = 'sek'

Question: What code is used to represent the currency of Croatian Kuna?
SQL: SELECT "code" FROM euro_convergence WHERE "currency" = 'croatian kuna'