convert ISO 3166-1 countries code from alpha-3 to alpha-2

iso-3166-1-alpha3to2.sql

UPDATE table SET column = 'AD' WHERE column = 'AND';
UPDATE table SET column = 'AE' WHERE column = 'ARE';
UPDATE table SET column = 'AF' WHERE column = 'AFG';
UPDATE table SET column = 'AG' WHERE column = 'ATG';
UPDATE table SET column = 'AI' WHERE column = 'AIA';
UPDATE table SET column = 'AL' WHERE column = 'ALB';
UPDATE table SET column = 'AM' WHERE column = 'ARM';
UPDATE table SET column = 'AN' WHERE column = 'ANT';
UPDATE table SET column = 'AO' WHERE column = 'AGO';
UPDATE table SET column = 'AQ' WHERE column = 'ATA';
UPDATE table SET column = 'AR' WHERE column = 'ARG';
UPDATE table SET column = 'AS' WHERE column = 'ASM';
UPDATE table SET column = 'AT' WHERE column = 'AUT';
UPDATE table SET column = 'AU' WHERE column = 'AUS';
UPDATE table SET column = 'AW' WHERE column = 'ABW';
UPDATE table SET column = 'AX' WHERE column = 'ALA';
UPDATE table SET column = 'AZ' WHERE column = 'AZE';
UPDATE table SET column = 'BA' WHERE column = 'BIH';
UPDATE table SET column = 'BB' WHERE column = 'BRB';
UPDATE table SET column = 'BD' WHERE column = 'BGD';
UPDATE table SET column = 'BE' WHERE column = 'BEL';
UPDATE table SET column = 'BF' WHERE column = 'BFA';
UPDATE table SET column = 'BG' WHERE column = 'BGR';
UPDATE table SET column = 'BH' WHERE column = 'BHR';
UPDATE table SET column = 'BI' WHERE column = 'BDI';
UPDATE table SET column = 'BJ' WHERE column = 'BEN';
UPDATE table SET column = 'BM' WHERE column = 'BMU';
UPDATE table SET column = 'BN' WHERE column = 'BRN';
UPDATE table SET column = 'BO' WHERE column = 'BOL';
UPDATE table SET column = 'BR' WHERE column = 'BRA';
UPDATE table SET column = 'BS' WHERE column = 'BHS';
UPDATE table SET column = 'BT' WHERE column = 'BTN';
UPDATE table SET column = 'BV' WHERE column = 'BVT';
UPDATE table SET column = 'BW' WHERE column = 'BWA';
UPDATE table SET column = 'BY' WHERE column = 'BLR';
UPDATE table SET column = 'BZ' WHERE column = 'BLZ';
UPDATE table SET column = 'CA' WHERE column = 'CAN';
UPDATE table SET column = 'CC' WHERE column = 'CCK';
UPDATE table SET column = 'CD' WHERE column = 'COD';
UPDATE table SET column = 'CF' WHERE column = 'CAF';
UPDATE table SET column = 'CG' WHERE column = 'COG';
UPDATE table SET column = 'CH' WHERE column = 'CHE';
UPDATE table SET column = 'CI' WHERE column = 'CIV';
UPDATE table SET column = 'CK' WHERE column = 'COK';
UPDATE table SET column = 'CL' WHERE column = 'CHL';
UPDATE table SET column = 'CM' WHERE column = 'CMR';
UPDATE table SET column = 'CN' WHERE column = 'CHN';
UPDATE table SET column = 'CO' WHERE column = 'COL';
UPDATE table SET column = 'CR' WHERE column = 'CRI';
UPDATE table SET column = 'CS' WHERE column = 'SCG';
UPDATE table SET column = 'CU' WHERE column = 'CUB';
UPDATE table SET column = 'CV' WHERE column = 'CPV';
UPDATE table SET column = 'CX' WHERE column = 'CXR';
UPDATE table SET column = 'CY' WHERE column = 'CYP';
UPDATE table SET column = 'CZ' WHERE column = 'CZE';
UPDATE table SET column = 'DE' WHERE column = 'DEU';
UPDATE table SET column = 'DJ' WHERE column = 'DJI';
UPDATE table SET column = 'DK' WHERE column = 'DNK';
UPDATE table SET column = 'DM' WHERE column = 'DMA';
UPDATE table SET column = 'DO' WHERE column = 'DOM';
UPDATE table SET column = 'DZ' WHERE column = 'DZA';
UPDATE table SET column = 'EC' WHERE column = 'ECU';
UPDATE table SET column = 'EE' WHERE column = 'EST';
UPDATE table SET column = 'EG' WHERE column = 'EGY';
UPDATE table SET column = 'EH' WHERE column = 'ESH';
UPDATE table SET column = 'ER' WHERE column = 'ERI';
UPDATE table SET column = 'ES' WHERE column = 'ESP';
UPDATE table SET column = 'ET' WHERE column = 'ETH';
UPDATE table SET column = 'FI' WHERE column = 'FIN';
UPDATE table SET column = 'FJ' WHERE column = 'FJI';
UPDATE table SET column = 'FK' WHERE column = 'FLK';
UPDATE table SET column = 'FM' WHERE column = 'FSM';
UPDATE table SET column = 'FO' WHERE column = 'FRO';
UPDATE table SET column = 'FR' WHERE column = 'FRA';
UPDATE table SET column = 'GA' WHERE column = 'GAB';
UPDATE table SET column = 'GB' WHERE column = 'GBR';
UPDATE table SET column = 'GD' WHERE column = 'GRD';
UPDATE table SET column = 'GE' WHERE column = 'GEO';
UPDATE table SET column = 'GF' WHERE column = 'GUF';
UPDATE table SET column = 'GH' WHERE column = 'GHA';
UPDATE table SET column = 'GI' WHERE column = 'GIB';
UPDATE table SET column = 'GL' WHERE column = 'GRL';
UPDATE table SET column = 'GM' WHERE column = 'GMB';
UPDATE table SET column = 'GN' WHERE column = 'GIN';
UPDATE table SET column = 'GP' WHERE column = 'GLP';
UPDATE table SET column = 'GQ' WHERE column = 'GNQ';
UPDATE table SET column = 'GR' WHERE column = 'GRC';
UPDATE table SET column = 'GS' WHERE column = 'SGS';
UPDATE table SET column = 'GT' WHERE column = 'GTM';
UPDATE table SET column = 'GU' WHERE column = 'GUM';
UPDATE table SET column = 'GW' WHERE column = 'GNB';
UPDATE table SET column = 'GY' WHERE column = 'GUY';
UPDATE table SET column = 'HK' WHERE column = 'HKG';
UPDATE table SET column = 'HM' WHERE column = 'HMD';
UPDATE table SET column = 'HN' WHERE column = 'HND';
UPDATE table SET column = 'HR' WHERE column = 'HRV';
UPDATE table SET column = 'HT' WHERE column = 'HTI';
UPDATE table SET column = 'HU' WHERE column = 'HUN';
UPDATE table SET column = 'ID' WHERE column = 'IDN';
UPDATE table SET column = 'IE' WHERE column = 'IRL';
UPDATE table SET column = 'IL' WHERE column = 'ISR';
UPDATE table SET column = 'IN' WHERE column = 'IND';
UPDATE table SET column = 'IO' WHERE column = 'IOT';
UPDATE table SET column = 'IQ' WHERE column = 'IRQ';
UPDATE table SET column = 'IR' WHERE column = 'IRN';
UPDATE table SET column = 'IS' WHERE column = 'ISL';
UPDATE table SET column = 'IT' WHERE column = 'ITA';
UPDATE table SET column = 'JM' WHERE column = 'JAM';
UPDATE table SET column = 'JO' WHERE column = 'JOR';
UPDATE table SET column = 'JP' WHERE column = 'JPN';
UPDATE table SET column = 'KE' WHERE column = 'KEN';
UPDATE table SET column = 'KG' WHERE column = 'KGZ';
UPDATE table SET column = 'KH' WHERE column = 'KHM';
UPDATE table SET column = 'KI' WHERE column = 'KIR';
UPDATE table SET column = 'KM' WHERE column = 'COM';
UPDATE table SET column = 'KN' WHERE column = 'KNA';
UPDATE table SET column = 'KP' WHERE column = 'PRK';
UPDATE table SET column = 'KR' WHERE column = 'KOR';
UPDATE table SET column = 'KW' WHERE column = 'KWT';
UPDATE table SET column = 'KY' WHERE column = 'CYM';
UPDATE table SET column = 'KZ' WHERE column = 'KAZ';
UPDATE table SET column = 'LA' WHERE column = 'LAO';
UPDATE table SET column = 'LB' WHERE column = 'LBN';
UPDATE table SET column = 'LC' WHERE column = 'LCA';
UPDATE table SET column = 'LI' WHERE column = 'LIE';
UPDATE table SET column = 'LK' WHERE column = 'LKA';
UPDATE table SET column = 'LR' WHERE column = 'LBR';
UPDATE table SET column = 'LS' WHERE column = 'LSO';
UPDATE table SET column = 'LT' WHERE column = 'LTU';
UPDATE table SET column = 'LU' WHERE column = 'LUX';
UPDATE table SET column = 'LV' WHERE column = 'LVA';
UPDATE table SET column = 'LY' WHERE column = 'LBY';
UPDATE table SET column = 'MA' WHERE column = 'MAR';
UPDATE table SET column = 'MC' WHERE column = 'MCO';
UPDATE table SET column = 'MD' WHERE column = 'MDA';
UPDATE table SET column = 'MG' WHERE column = 'MDG';
UPDATE table SET column = 'MH' WHERE column = 'MHL';
UPDATE table SET column = 'MK' WHERE column = 'MKD';
UPDATE table SET column = 'ML' WHERE column = 'MLI';
UPDATE table SET column = 'MM' WHERE column = 'MMR';
UPDATE table SET column = 'MN' WHERE column = 'MNG';
UPDATE table SET column = 'MO' WHERE column = 'MAC';
UPDATE table SET column = 'MP' WHERE column = 'MNP';
UPDATE table SET column = 'MQ' WHERE column = 'MTQ';
UPDATE table SET column = 'MR' WHERE column = 'MRT';
UPDATE table SET column = 'MS' WHERE column = 'MSR';
UPDATE table SET column = 'MT' WHERE column = 'MLT';
UPDATE table SET column = 'MU' WHERE column = 'MUS';
UPDATE table SET column = 'MV' WHERE column = 'MDV';
UPDATE table SET column = 'MW' WHERE column = 'MWI';
UPDATE table SET column = 'MX' WHERE column = 'MEX';
UPDATE table SET column = 'MY' WHERE column = 'MYS';
UPDATE table SET column = 'MZ' WHERE column = 'MOZ';
UPDATE table SET column = 'NA' WHERE column = 'NAM';
UPDATE table SET column = 'NC' WHERE column = 'NCL';
UPDATE table SET column = 'NE' WHERE column = 'NER';
UPDATE table SET column = 'NF' WHERE column = 'NFK';
UPDATE table SET column = 'NG' WHERE column = 'NGA';
UPDATE table SET column = 'NI' WHERE column = 'NIC';
UPDATE table SET column = 'NL' WHERE column = 'NLD';
UPDATE table SET column = 'NO' WHERE column = 'NOR';
UPDATE table SET column = 'NP' WHERE column = 'NPL';
UPDATE table SET column = 'NR' WHERE column = 'NRU';
UPDATE table SET column = 'NU' WHERE column = 'NIU';
UPDATE table SET column = 'NZ' WHERE column = 'NZL';
UPDATE table SET column = 'OM' WHERE column = 'OMN';
UPDATE table SET column = 'PA' WHERE column = 'PAN';
UPDATE table SET column = 'PE' WHERE column = 'PER';
UPDATE table SET column = 'PF' WHERE column = 'PYF';
UPDATE table SET column = 'PG' WHERE column = 'PNG';
UPDATE table SET column = 'PH' WHERE column = 'PHL';
UPDATE table SET column = 'PK' WHERE column = 'PAK';
UPDATE table SET column = 'PL' WHERE column = 'POL';
UPDATE table SET column = 'PM' WHERE column = 'SPM';
UPDATE table SET column = 'PN' WHERE column = 'PCN';
UPDATE table SET column = 'PR' WHERE column = 'PRI';
UPDATE table SET column = 'PS' WHERE column = 'PSE';
UPDATE table SET column = 'PT' WHERE column = 'PRT';
UPDATE table SET column = 'PW' WHERE column = 'PLW';
UPDATE table SET column = 'PY' WHERE column = 'PRY';
UPDATE table SET column = 'QA' WHERE column = 'QAT';
UPDATE table SET column = 'RE' WHERE column = 'REU';
UPDATE table SET column = 'RO' WHERE column = 'ROU';
UPDATE table SET column = 'RU' WHERE column = 'RUS';
UPDATE table SET column = 'RW' WHERE column = 'RWA';
UPDATE table SET column = 'SA' WHERE column = 'SAU';
UPDATE table SET column = 'SB' WHERE column = 'SLB';
UPDATE table SET column = 'SC' WHERE column = 'SYC';
UPDATE table SET column = 'SD' WHERE column = 'SDN';
UPDATE table SET column = 'SE' WHERE column = 'SWE';
UPDATE table SET column = 'SG' WHERE column = 'SGP';
UPDATE table SET column = 'SH' WHERE column = 'SHN';
UPDATE table SET column = 'SI' WHERE column = 'SVN';
UPDATE table SET column = 'SJ' WHERE column = 'SJM';
UPDATE table SET column = 'SK' WHERE column = 'SVK';
UPDATE table SET column = 'SL' WHERE column = 'SLE';
UPDATE table SET column = 'SM' WHERE column = 'SMR';
UPDATE table SET column = 'SN' WHERE column = 'SEN';
UPDATE table SET column = 'SO' WHERE column = 'SOM';
UPDATE table SET column = 'SR' WHERE column = 'SUR';
UPDATE table SET column = 'ST' WHERE column = 'STP';
UPDATE table SET column = 'SV' WHERE column = 'SLV';
UPDATE table SET column = 'SY' WHERE column = 'SYR';
UPDATE table SET column = 'SZ' WHERE column = 'SWZ';
UPDATE table SET column = 'TC' WHERE column = 'TCA';
UPDATE table SET column = 'TD' WHERE column = 'TCD';
UPDATE table SET column = 'TF' WHERE column = 'ATF';
UPDATE table SET column = 'TG' WHERE column = 'TGO';
UPDATE table SET column = 'TH' WHERE column = 'THA';
UPDATE table SET column = 'TJ' WHERE column = 'TJK';
UPDATE table SET column = 'TK' WHERE column = 'TKL';
UPDATE table SET column = 'TL' WHERE column = 'TLS';
UPDATE table SET column = 'TM' WHERE column = 'TKM';
UPDATE table SET column = 'TN' WHERE column = 'TUN';
UPDATE table SET column = 'TO' WHERE column = 'TON';
UPDATE table SET column = 'TR' WHERE column = 'TUR';
UPDATE table SET column = 'TT' WHERE column = 'TTO';
UPDATE table SET column = 'TV' WHERE column = 'TUV';
UPDATE table SET column = 'TW' WHERE column = 'TWN';
UPDATE table SET column = 'TZ' WHERE column = 'TZA';
UPDATE table SET column = 'UA' WHERE column = 'UKR';
UPDATE table SET column = 'UG' WHERE column = 'UGA';
UPDATE table SET column = 'UM' WHERE column = 'UMI';
UPDATE table SET column = 'US' WHERE column = 'USA';
UPDATE table SET column = 'UY' WHERE column = 'URY';
UPDATE table SET column = 'UZ' WHERE column = 'UZB';
UPDATE table SET column = 'VA' WHERE column = 'VAT';
UPDATE table SET column = 'VC' WHERE column = 'VCT';
UPDATE table SET column = 'VE' WHERE column = 'VEN';
UPDATE table SET column = 'VG' WHERE column = 'VGB';
UPDATE table SET column = 'VI' WHERE column = 'VIR';
UPDATE table SET column = 'VN' WHERE column = 'VNM';
UPDATE table SET column = 'VU' WHERE column = 'VUT';
UPDATE table SET column = 'WF' WHERE column = 'WLF';
UPDATE table SET column = 'WS' WHERE column = 'WSM';
UPDATE table SET column = 'YE' WHERE column = 'YEM';
UPDATE table SET column = 'YT' WHERE column = 'MYT';
UPDATE table SET column = 'ZA' WHERE column = 'ZAF';
UPDATE table SET column = 'ZM' WHERE column = 'ZMB';
UPDATE table SET column = 'ZW' WHERE column = 'ZWE';

This has been quite helpful to me, thanks for sharing 😄 Just a small detail, UPDATE table SET column = 'GB' WHERE column = 'GBR'; is done twice (not that it matters in this case, of course).

you're welcome! updated thanks