Does oracle provide a built-in currency table for me to use as constraints?

Question

I'm creating a table in Oracle 11g like this:

CREATE TABLE EXAMPLE (
    ID VARCHAR2(10) PRIMARY KEY,
    NAME VARCHAR2(100), 
    SHORT VARCHAR2(50),
    CURRENCY CHAR(3)
);

Is it possible to create a foreign key constraint or even a check constraint on CURRENCY to a built-in Oracle table that contains the ISO currencies?

Not having a great understanding of databases I also take as input other solutions that might be out there, however I do not want to maintain my own table for this, if it's too much work, I'll live with user errors.

Thanks.

Answer 1

Note: Edited to include @A.B.Cade's suggestion.

Unfortunately you can't directly add a constraint, as the currencies data is available through a system a view. You can, however, create your own table with that information and then create the foreign key. Here's an example of how you can do it.

CREATE TABLE currencies (
  country VARCHAR2(30) PRIMARY KEY,
  currency VARCHAR2(3) NOT NULL
);

INSERT INTO currencies
  SELECT value country, utl_i18n.get_default_iso_currency(value) currency
    FROM v$nls_valid_values
   WHERE parameter = 'TERRITORY';

CREATE INDEX currencies_iso_idx ON currencies(currency) COMPUTE STATISTICS;

ALTER TABLE example ADD CONSTRAINT example_currency_fk FOREIGN KEY (currency)
  REFERENCES currencies(currency);

The example above includes an index on the currency value, as I suspect that will what you'll be querying on.

Answer 2

You can get a list of ISO currencies from a built in view in oracle:

select utl_i18n.GET_DEFAULT_ISO_CURRENCY(value) iso_cur
from v$nls_valid_values
where parameter = 'TERRITORY'

But as Nuno Guerreiro said, you'll need to create a table from these results and add a foreign key to the new table.

Answer 3

Actually I don't understand what do you mean by "default Oracle table that contains ISO currencies" (do you mean Oracle PeopleSoft CURRENCY_CD_TBL table?), but in general you can alter your table after creation to add foreign key constraint. Here is an example:

    ALTER TABLE EXAMPLE
    ADD CONSTRAINT fk_currency
      FOREIGN KEY (CURRENCY)
      REFERENCES put_parent_table_name_here(_corresponding_field_name_in_perent_table); 

You also can add constraint definition into CREATE TABLE statement. Here is an example:

    CREATE TABLE EXAMPLE (
        ID VARCHAR2(10) PRIMARY KEY,
        NAME VARCHAR2(100), 
        SHORT VARCHAR2(50),
        CURRENCY CHAR(3),
      CONSTRAINT fk_currency
      FOREIGN KEY (CURRENCY)
      REFERENCES put_parent_table_name_here(_corresponding_field_name_in_perent_table)
    );