Blog
Aug 01, 2022

How to Convert ISO Code to Full Country Name in Postgres?

ISO 3166-1 alpha-2 is a popular standard to represent countries using a short two-letter code. You might have already encountered them: IN, US, GB. They are used everywhere to ensure consistency with countries as full names are prone to minor differences.

But when you’re actually querying the data it makes sense to map them to their full names as shortcodes aren’t easy to parse.

A popular approach to do this has been to create a separate table. Seed it with ISO country data then JOIN it with the table which you’re querying. Personally, I feel this is too big of a hassle for a minor task. Additionally, you might not even have a choice as your access to the database might be limited to just reading data.

A better alternative is to create a UDF, which accepts the country code and returns the full name. Yes, the function’s definition would be relatively long but it needs to be defined only once. It would involve fewer steps and the approach is flexible.

First, let’s get a JSON of ISO country codes and their full names. This gist provides a good updated list.

Postgres provides many handy functions to query JSONs. We can use json_each_text to query the above JSON. The function expands the JSON object into key-value pairs. So:

SELECT * FROM json_each_text('{
  "AF": "Afghanistan",
  "AX": "Aland Islands",
  "AL": "Albania",
  "AI": "Anguilla",
  "AQ": "Antarctica",
  ....
}');

Becomes:

key value
AF Afghanistan
AX Aland Islands
AL Albania
DZ Algeria
AS American Samoa
AD Andorra
AO Angola
AI Anguilla
AQ Antarctica
AG Antigua And Barbuda
AR Argentina
AM Armenia
AW Aruba
AU Australia

To return the full country name for the ISO code, we can do:

SELECT value AS country FROM json_each_text('{
  "AF": "Afghanistan",
  "AX": "Aland Islands",
  "AL": "Albania",
  ...
}') WHERE key = 'US';

This will output: United States.

Now, we can create our UDF to do the exact thing with the argument:

CREATE OR REPLACE FUNCTION full_country(country text) RETURNS text AS $$
    SELECT value FROM json_each_text('{"AF":"Afghanistan","AX":"Aland Islands","AL":"Albania","DZ":"Algeria","AS":"American Samoa","AD":"Andorra","AO":"Angola","AI":"Anguilla","AQ":"Antarctica","AG":"Antigua And Barbuda","AR":"Argentina","AM":"Armenia","AW":"Aruba","AU":"Australia","AT":"Austria","AZ":"Azerbaijan","BS":"Bahamas","BH":"Bahrain","BD":"Bangladesh","BB":"Barbados","BY":"Belarus","BE":"Belgium","BZ":"Belize","BJ":"Benin","BM":"Bermuda","BT":"Bhutan","BO":"Bolivia","BA":"Bosnia And Herzegovina","BW":"Botswana","BV":"Bouvet Island","BR":"Brazil","IO":"British Indian Ocean Territory","BN":"Brunei Darussalam","BG":"Bulgaria","BF":"Burkina Faso","BI":"Burundi","KH":"Cambodia","CM":"Cameroon","CA":"Canada","CV":"Cape Verde","KY":"Cayman Islands","CF":"Central African Republic","TD":"Chad","CL":"Chile","CN":"China","CX":"Christmas Island","CC":"Cocos (Keeling) Islands","CO":"Colombia","KM":"Comoros","CG":"Congo","CD":"Congo, Democratic Republic","CK":"Cook Islands","CR":"Costa Rica","CI":"Cote D\"Ivoire","HR":"Croatia","CU":"Cuba","CY":"Cyprus","CZ":"Czech Republic","DK":"Denmark","DJ":"Djibouti","DM":"Dominica","DO":"Dominican Republic","EC":"Ecuador","EG":"Egypt","SV":"El Salvador","GQ":"Equatorial Guinea","ER":"Eritrea","EE":"Estonia","ET":"Ethiopia","FK":"Falkland Islands (Malvinas)","FO":"Faroe Islands","FJ":"Fiji","FI":"Finland","FR":"France","GF":"French Guiana","PF":"French Polynesia","TF":"French Southern Territories","GA":"Gabon","GM":"Gambia","GE":"Georgia","DE":"Germany","GH":"Ghana","GI":"Gibraltar","GR":"Greece","GL":"Greenland","GD":"Grenada","GP":"Guadeloupe","GU":"Guam","GT":"Guatemala","GG":"Guernsey","GN":"Guinea","GW":"Guinea-Bissau","GY":"Guyana","HT":"Haiti","HM":"Heard Island & Mcdonald Islands","VA":"Holy See (Vatican City State)","HN":"Honduras","HK":"Hong Kong","HU":"Hungary","IS":"Iceland","IN":"India","ID":"Indonesia","IR":"Iran, Islamic Republic Of","IQ":"Iraq","IE":"Ireland","IM":"Isle Of Man","IL":"Israel","IT":"Italy","JM":"Jamaica","JP":"Japan","JE":"Jersey","JO":"Jordan","KZ":"Kazakhstan","KE":"Kenya","KI":"Kiribati","KR":"Korea","KP":"North Korea","KW":"Kuwait","KG":"Kyrgyzstan","LA":"Lao People\"s Democratic Republic","LV":"Latvia","LB":"Lebanon","LS":"Lesotho","LR":"Liberia","LY":"Libyan Arab Jamahiriya","LI":"Liechtenstein","LT":"Lithuania","LU":"Luxembourg","MO":"Macao","MK":"Macedonia","MG":"Madagascar","MW":"Malawi","MY":"Malaysia","MV":"Maldives","ML":"Mali","MT":"Malta","MH":"Marshall Islands","MQ":"Martinique","MR":"Mauritania","MU":"Mauritius","YT":"Mayotte","MX":"Mexico","FM":"Micronesia, Federated States Of","MD":"Moldova","MC":"Monaco","MN":"Mongolia","ME":"Montenegro","MS":"Montserrat","MA":"Morocco","MZ":"Mozambique","MM":"Myanmar","NA":"Namibia","NR":"Nauru","NP":"Nepal","NL":"Netherlands","AN":"Netherlands Antilles","NC":"New Caledonia","NZ":"New Zealand","NI":"Nicaragua","NE":"Niger","NG":"Nigeria","NU":"Niue","NF":"Norfolk Island","MP":"Northern Mariana Islands","NO":"Norway","OM":"Oman","PK":"Pakistan","PW":"Palau","PS":"Palestinian Territory, Occupied","PA":"Panama","PG":"Papua New Guinea","PY":"Paraguay","PE":"Peru","PH":"Philippines","PN":"Pitcairn","PL":"Poland","PT":"Portugal","PR":"Puerto Rico","QA":"Qatar","RE":"Reunion","RO":"Romania","RU":"Russian Federation","RW":"Rwanda","BL":"Saint Barthelemy","SH":"Saint Helena","KN":"Saint Kitts And Nevis","LC":"Saint Lucia","MF":"Saint Martin","PM":"Saint Pierre And Miquelon","VC":"Saint Vincent And Grenadines","WS":"Samoa","SM":"San Marino","ST":"Sao Tome And Principe","SA":"Saudi Arabia","SN":"Senegal","RS":"Serbia","SC":"Seychelles","SL":"Sierra Leone","SG":"Singapore","SK":"Slovakia","SI":"Slovenia","SB":"Solomon Islands","SO":"Somalia","ZA":"South Africa","GS":"South Georgia And Sandwich Isl.","ES":"Spain","LK":"Sri Lanka","SD":"Sudan","SR":"Suriname","SJ":"Svalbard And Jan Mayen","SZ":"Swaziland","SE":"Sweden","CH":"Switzerland","SY":"Syrian Arab Republic","TW":"Taiwan","TJ":"Tajikistan","TZ":"Tanzania","TH":"Thailand","TL":"Timor-Leste","TG":"Togo","TK":"Tokelau","TO":"Tonga","TT":"Trinidad And Tobago","TN":"Tunisia","TR":"Turkey","TM":"Turkmenistan","TC":"Turks And Caicos Islands","TV":"Tuvalu","UG":"Uganda","UA":"Ukraine","AE":"United Arab Emirates","GB":"United Kingdom","US":"United States","UM":"United States Outlying Islands","UY":"Uruguay","UZ":"Uzbekistan","VU":"Vanuatu","VE":"Venezuela","VN":"Vietnam","VG":"Virgin Islands, British","VI":"Virgin Islands, U.S.","WF":"Wallis And Futuna","EH":"Western Sahara","YE":"Yemen","ZM":"Zambia","ZW":"Zimbabwe"}') WHERE key = UPPER(country);
$$ LANGUAGE SQL;

We can use the function like:

SELECT full_country('in');

Output: India