Question

what’s the best way to localize a database table, holding for example a Country?

1 Flat Table

CountryID|Code|NameEN|NameIT
----------------------------
1        |IT  |Italy |Italia

SELECT CountryID, Code, NameEN AS Name
FROM Countries

2 Joined Tables

CountryID|Code
--------------
1        |IT

CountryID|LocalizationCode|Name
---------------------------------
1        |EN              |Italy
---------------------------------
2        |IT              |Italia

SELECT CountryID, Code, Name
FROM Countries INNER JOIN CountriesLoc ON Countries.CountryID = CountriesLocs.CountryID
WHERE LocalizationCode = 'EN'

Thank you!

Answer 1

I recommend going with the second option, although you appear to have some data-typos.

Country:

Id  Code
===============
1   IT

Localized_Country:

CountryId  LanguageCode  LocalizedName
=========================================
1          IT            Italia
1          EN            Italy

Which you then query like so:

SELECT a.Id, b.LocalizedName
FROM Country as a
JOIN Localized_Country as b
ON b.CountryId = a.Id
AND b.LanguageCode = :InputLanguageCode
WHERE a.Code = :InputInternationalCountryCode

Wrap that (or something similar) up in a view, and you’re golden.

Some recommendations:
You may want to push Language (or some other type of Locale concept) into it’s own table. The key can either be an auto-increment value, or the international characters, doesn’t much matter which.
Make sure to put a unique constraint on (CountryId, LanguageCode), just in case. And never forget your foreign keys.