[RESOLVED] Search for parts of a string within a string

[ChetUbetcha]

I have two fields that have comma separated strings

ID1 may contain 1,2,3,4
ID2 may contain 1,2,3
ID3 may contain 3,4
ID4 may contain 5,6

I want to take ID1 and search for any other IDs that contain at least 1,2,3 or 4 and return the IDs that match. In this case, it would be ID1, ID2 and ID3.

[laserlight]

There may be database vendor specific SQL functions that you can use, but instead of using them, normalise your database by introducing new tables to replace your multi-valued fields.

You can read this article for an overview of what I am talking about: Managing Many to Many Relationships in MySQL - Part 1

You could also read this PHP Builder article for an introduction to normalisation (though I believe that it has minor inaccuracies) :
Database Normalization and Design Techniques