CREATE TABLE t(s,w) AS SELECT 'I do not control the speed at which lobsters die', 'code' FROM DUAL UNION ALL SELECT 'testcase string', 'tas' FROM DUAL UNION ALL SELECT 'uglhwagp qvyntzmf','ulhwagpqvyntzmf' FROM DUAL UNION ALL SELECT 'qrkacxx wwfja jsyjdffa vwfgxf','qcfvf' FROM DUAL UNION ALL SELECT 'z wzsgovhh jopw igcx muxj xmmisxdn t lmb','gcujxlb' FROM DUAL UNION ALL SELECT 'kxf jgmzejypb ya','e' FROM DUAL UNION ALL SELECT 'fe oxyk y','ex' FROM DUAL UNION ALL SELECT 'o wr fmik','owrfmik' FROM DUAL UNION ALL SELECT 'pgezt yozcyqq drxt gcvaj hx l ix xemimmox','e' FROM DUAL UNION ALL SELECT 'kqclk b hkgtrh','k' FROM DUAL UNION ALL SELECT 'sia prcrdfckg otqwvdv wzdqxvqb h xclxmaj xjdwt lzfw','crwqqhxl' FROM DUAL UNION ALL SELECT 'teatsase','tas' FROM DUAL;

WITH r(sentence,word,sentence_pos,word_pos,output,len)AS( SELECT s, w, 1, 1, '', LENGTH(s) FROM t UNION ALL SELECT sentence, word, sentence_pos+1, DECODE( SUBSTR(sentence,sentence_pos,1), SUBSTR(word,word_pos,1), word_pos+1, word_pos ), output||DECODE( SUBSTR(sentence,sentence_pos,1), SUBSTR(word,word_pos,1), SUBSTR(word,word_pos,1), 0 ), len FROM r WHERE sentence_pos<=len ) SELECT sentence, word, output FROM r WHERE sentence_pos>len

WITH r(s,w,a,b,c,l)AS(SELECT s,w,1,1,'',LENGTH(s) FROM t UNION ALL SELECT s,w,a+1,DECODE(SUBSTR(s,a,1),SUBSTR(w,b,1),b+1,b),c||DECODE(SUBSTR(s,a,1),SUBSTR(w,b,1),SUBSTR(w,b,1),0),l FROM r WHERE a<=l)SELECT c FROM r WHERE a>l