Question

I have a table with a column containing a list (yes I know this violates normalization). I’m trying to find some sore of “overlap” function i.e.

SELECT * FROM TABLE WHERE 'a,b,c' OVERLAP TABLE.LISTCOLUMN 

So, LISTCOLUMNcontains any or all of a, b, or c

Answer 1

Two options:

Use regexp_like, if you’re using Oracle 10g or above:

select *
  from my_table
 where regexp_like(listcolumn, '[abc]')

This matches everything from your table where a or b or c is in the column.

Alternatively you can do the more horrible and difficult to maintain:

select *
  from my_table
 where listcolumn like '%a%'
    or listcolumn like '%b%'
    or listcolumn like '%c%'

Here’s a little SQL Fiddle to demonstrate.

However, as you already know, normalising your database properly will save you a lot of pain in the longer run.