SELECT countries alpha-3 to alpha-2

gistfile1.txt

select CASE alpha3
    WHEN 'ABH' then 'AB'
    WHEN 'AND' then 'AD'
    WHEN 'ARE' then 'AE'
    WHEN 'AFG' then 'AF'
    WHEN 'ATG' then 'AG'
    WHEN 'AIA' then 'AI'
    WHEN 'ALB' then 'AL'
    WHEN 'ARM' then 'AM'
    WHEN 'AGO' then 'AO'
    WHEN 'ATA' then 'AQ'
    WHEN 'ARG' then 'AR'
    WHEN 'ASM' then 'AS'
    WHEN 'AUT' then 'AT'
    WHEN 'AUS' then 'AU'
    WHEN 'ABW' then 'AW'
    WHEN 'ALA' then 'AX'
    WHEN 'AZE' then 'AZ'
    WHEN 'BIH' then 'BA'
    WHEN 'BRB' then 'BB'
    WHEN 'BGD' then 'BD'
    WHEN 'BEL' then 'BE'
    WHEN 'BFA' then 'BF'
    WHEN 'BGR' then 'BG'
    WHEN 'BHR' then 'BH'
    WHEN 'BDI' then 'BI'
    WHEN 'BEN' then 'BJ'
    WHEN 'BLM' then 'BL'
    WHEN 'BMU' then 'BM'
    WHEN 'BRN' then 'BN'
    WHEN 'BOL' then 'BO'
    WHEN 'BES' then 'BQ'
    WHEN 'BRA' then 'BR'
    WHEN 'BHS' then 'BS'
    WHEN 'BTN' then 'BT'
    WHEN 'BVT' then 'BV'
    WHEN 'BWA' then 'BW'
    WHEN 'BLR' then 'BY'
    WHEN 'BLZ' then 'BZ'
    WHEN 'CAN' then 'CA'
    WHEN 'CCK' then 'CC'
    WHEN 'COD' then 'CD'
    WHEN 'CAF' then 'CF'
    WHEN 'COG' then 'CG'
    WHEN 'CHE' then 'CH'
    WHEN 'CIV' then 'CI'
    WHEN 'COK' then 'CK'
    WHEN 'CHL' then 'CL'
    WHEN 'CMR' then 'CM'
    WHEN 'CHN' then 'CN'
    WHEN 'COL' then 'CO'
    WHEN 'CRI' then 'CR'
    WHEN 'CUB' then 'CU'
    WHEN 'CPV' then 'CV'
    WHEN 'CUW' then 'CW'
    WHEN 'CXR' then 'CX'
    WHEN 'CYP' then 'CY'
    WHEN 'CZE' then 'CZ'
    WHEN 'DEU' then 'DE'
    WHEN 'DJI' then 'DJ'
    WHEN 'DNK' then 'DK'
    WHEN 'DMA' then 'DM'
    WHEN 'DOM' then 'DO'
    WHEN 'DZA' then 'DZ'
    WHEN 'ECU' then 'EC'
    WHEN 'EST' then 'EE'
    WHEN 'EGY' then 'EG'
    WHEN 'ESH' then 'EH'
    WHEN 'ERI' then 'ER'
    WHEN 'ESP' then 'ES'
    WHEN 'ETH' then 'ET'
    WHEN 'FIN' then 'FI'
    WHEN 'FJI' then 'FJ'
    WHEN 'FLK' then 'FK'
    WHEN 'FSM' then 'FM'
    WHEN 'FRO' then 'FO'
    WHEN 'FRA' then 'FR'
    WHEN 'GAB' then 'GA'
    WHEN 'GBR' then 'GB'
    WHEN 'GRD' then 'GD'
    WHEN 'GEO' then 'GE'
    WHEN 'GUF' then 'GF'
    WHEN 'GGY' then 'GG'
    WHEN 'GHA' then 'GH'
    WHEN 'GIB' then 'GI'
    WHEN 'GRL' then 'GL'
    WHEN 'GMB' then 'GM'
    WHEN 'GIN' then 'GN'
    WHEN 'GLP' then 'GP'
    WHEN 'GNQ' then 'GQ'
    WHEN 'GRC' then 'GR'
    WHEN 'SGS' then 'GS'
    WHEN 'GTM' then 'GT'
    WHEN 'GUM' then 'GU'
    WHEN 'GNB' then 'GW'
    WHEN 'GUY' then 'GY'
    WHEN 'HKG' then 'HK'
    WHEN 'HMD' then 'HM'
    WHEN 'HND' then 'HN'
    WHEN 'HRV' then 'HR'
    WHEN 'HTI' then 'HT'
    WHEN 'HUN' then 'HU'
    WHEN 'IDN' then 'ID'
    WHEN 'IRL' then 'IE'
    WHEN 'ISR' then 'IL'
    WHEN 'IMN' then 'IM'
    WHEN 'IND' then 'IN'
    WHEN 'IOT' then 'IO'
    WHEN 'IRQ' then 'IQ'
    WHEN 'IRN' then 'IR'
    WHEN 'ISL' then 'IS'
    WHEN 'ITA' then 'IT'
    WHEN 'JEY' then 'JE'
    WHEN 'JAM' then 'JM'
    WHEN 'JOR' then 'JO'
    WHEN 'JPN' then 'JP'
    WHEN 'KEN' then 'KE'
    WHEN 'KGZ' then 'KG'
    WHEN 'KHM' then 'KH'
    WHEN 'KIR' then 'KI'
    WHEN 'COM' then 'KM'
    WHEN 'KNA' then 'KN'
    WHEN 'PRK' then 'KP'
    WHEN 'KOR' then 'KR'
    WHEN 'KWT' then 'KW'
    WHEN 'CYM' then 'KY'
    WHEN 'KAZ' then 'KZ'
    WHEN 'LAO' then 'LA'
    WHEN 'LBN' then 'LB'
    WHEN 'LCA' then 'LC'
    WHEN 'LIE' then 'LI'
    WHEN 'LKA' then 'LK'
    WHEN 'LBR' then 'LR'
    WHEN 'LSO' then 'LS'
    WHEN 'LTU' then 'LT'
    WHEN 'LUX' then 'LU'
    WHEN 'LVA' then 'LV'
    WHEN 'LBY' then 'LY'
    WHEN 'MAR' then 'MA'
    WHEN 'MCO' then 'MC'
    WHEN 'MDA' then 'MD'
    WHEN 'MNE' then 'ME'
    WHEN 'MAF' then 'MF'
    WHEN 'MDG' then 'MG'
    WHEN 'MHL' then 'MH'
    WHEN 'MKD' then 'MK'
    WHEN 'MLI' then 'ML'
    WHEN 'MMR' then 'MM'
    WHEN 'MNG' then 'MN'
    WHEN 'MAC' then 'MO'
    WHEN 'MNP' then 'MP'
    WHEN 'MTQ' then 'MQ'
    WHEN 'MRT' then 'MR'
    WHEN 'MSR' then 'MS'
    WHEN 'MLT' then 'MT'
    WHEN 'MUS' then 'MU'
    WHEN 'MDV' then 'MV'
    WHEN 'MWI' then 'MW'
    WHEN 'MEX' then 'MX'
    WHEN 'MYS' then 'MY'
    WHEN 'MOZ' then 'MZ'
    WHEN 'NAM' then 'NA'
    WHEN 'NCL' then 'NC'
    WHEN 'NER' then 'NE'
    WHEN 'NFK' then 'NF'
    WHEN 'NGA' then 'NG'
    WHEN 'NIC' then 'NI'
    WHEN 'NLD' then 'NL'
    WHEN 'NOR' then 'NO'
    WHEN 'NPL' then 'NP'
    WHEN 'NRU' then 'NR'
    WHEN 'NIU' then 'NU'
    WHEN 'NZL' then 'NZ'
    WHEN 'OMN' then 'OM'
    WHEN 'OST' then 'OS'
    WHEN 'PAN' then 'PA'
    WHEN 'PER' then 'PE'
    WHEN 'PYF' then 'PF'
    WHEN 'PNG' then 'PG'
    WHEN 'PHL' then 'PH'
    WHEN 'PAK' then 'PK'
    WHEN 'POL' then 'PL'
    WHEN 'SPM' then 'PM'
    WHEN 'PCN' then 'PN'
    WHEN 'PRI' then 'PR'
    WHEN 'PSE' then 'PS'
    WHEN 'PRT' then 'PT'
    WHEN 'PLW' then 'PW'
    WHEN 'PRY' then 'PY'
    WHEN 'QAT' then 'QA'
    WHEN 'REU' then 'RE'
    WHEN 'ROU' then 'RO'
    WHEN 'SRB' then 'RS'
    WHEN 'RUS' then 'RU'
    WHEN 'RWA' then 'RW'
    WHEN 'SAU' then 'SA'
    WHEN 'SLB' then 'SB'
    WHEN 'SYC' then 'SC'
    WHEN 'SDN' then 'SD'
    WHEN 'SWE' then 'SE'
    WHEN 'SGP' then 'SG'
    WHEN 'SHN' then 'SH'
    WHEN 'SVN' then 'SI'
    WHEN 'SJM' then 'SJ'
    WHEN 'SVK' then 'SK'
    WHEN 'SLE' then 'SL'
    WHEN 'SMR' then 'SM'
    WHEN 'SEN' then 'SN'
    WHEN 'SOM' then 'SO'
    WHEN 'SUR' then 'SR'
    WHEN 'SSD' then 'SS'
    WHEN 'STP' then 'ST'
    WHEN 'SLV' then 'SV'
    WHEN 'SXM' then 'SX'
    WHEN 'SYR' then 'SY'
    WHEN 'SWZ' then 'SZ'
    WHEN 'TCA' then 'TC'
    WHEN 'TCD' then 'TD'
    WHEN 'ATF' then 'TF'
    WHEN 'TGO' then 'TG'
    WHEN 'THA' then 'TH'
    WHEN 'TJK' then 'TJ'
    WHEN 'TKL' then 'TK'
    WHEN 'TLS' then 'TL'
    WHEN 'TKM' then 'TM'
    WHEN 'TUN' then 'TN'
    WHEN 'TON' then 'TO'
    WHEN 'TUR' then 'TR'
    WHEN 'TTO' then 'TT'
    WHEN 'TUV' then 'TV'
    WHEN 'TWN' then 'TW'
    WHEN 'TZA' then 'TZ'
    WHEN 'UKR' then 'UA'
    WHEN 'UGA' then 'UG'
    WHEN 'UMI' then 'UM'
    WHEN 'USA' then 'US'
    WHEN 'URY' then 'UY'
    WHEN 'UZB' then 'UZ'
    WHEN 'VAT' then 'VA'
    WHEN 'VCT' then 'VC'
    WHEN 'VEN' then 'VE'
    WHEN 'VGB' then 'VG'
    WHEN 'VIR' then 'VI'
    WHEN 'VNM' then 'VN'
    WHEN 'VUT' then 'VU'
    WHEN 'WLF' then 'WF'
    WHEN 'WSM' then 'WS'
    WHEN 'YEM' then 'YE'
    WHEN 'MYT' then 'YT'
    WHEN 'ZAF' then 'ZA'
    WHEN 'ZMB' then 'ZM'
    WHEN 'ZWE' then 'ZW'
    ELSE 'Undefined' 
	END as alpha2
from countries;