Question

In oracle 11g, how can I convert character data in a column that falls under [a-z][A-Z] to some random char x. For example: if my source column data is tom then I should get xxx and if my source column data is lilly then I should get xxxxx.

Answer 1

You can write:

REGEXP_REPLACE(name_of_source_column, '[a-zA-Z]', 'x')
  AS source_column_with_letters_replaced_by_x

(except, of course, that source_column_with_letters_replaced_by_x is not a valid identifier in Oracle).