re = /:(?=([^']*'[^']*')*[^']*$)/
str = 'select id, :DATA_INI, \':DATA_INI\', titulo,
date_format(data_criacao,\'%d/%m/%Y %H:%i\') str_data_criacao
from v$sugestoes
where data_criacao between :DATA_INI AND :DATA_FIM AND \':TEST\'
and \'test \'\'string :DATA_INI \'\' :DATA_INI \'
order by data_criacao'
subst = '@'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html