Dynamic Tables

[mramazen]

I'm thinking about making a web site where users are given a set of general fields.

I would like for them to be able to add their own form elements and have their database table updated to reflect their new fields.

I'm considering giving each user a child (unique) table for this solution and linking it to the parent table.

Let's say I want 2 tables to be extended by the user.
So, each user would get it's own child table, if they decide to extend.
Potentially, this could create a lot of tables.

The way I envision creating it is very easy to code, but that doesn't mean it is the best way. What are some other ways I could accomplish this, and using this methods, what are some security and performance concerns I should consider?

Thanks

[tomhath]

Why a separate table for each user? Wouldn't it be easier to keep it all in one table and select rows by userid?