select "lower"(substr('Abc_de_fghijkl_mn', 1, 1)) || substr(replace(REGEXP_REPLACE(INITCAP('abc_de_fghijkl_mn'), '(w)[_]', '1') ,'_',''),2)
select lower(substr('Abc_de_fghijkl_mn', 1, 1)) || substr(replace(initcap(replace('Abc_de_fghijkl_mn', '_',' ')),' ',''),2)
select upper(substr('Abc_de_fghijkl_mn', 1, 1)) || substr(replace(initcap(replace('Abc_de_fghijkl_mn', '_',' ')),' ',''),2)