SQL query to correct wrong Customer Group ID's

[ukbaz]

Hi am upgrading from Prestahop 1.6 to 1.7 and have come across an issue I'd like to sort.  My customer group ID's currently are:

1. Customers

2. Visitor

3.Guest

These have been same since we started using Prestashop years ago. I believe at one point during an upgrade these should have changed to:

1. Vistor

2. Guest

3. Customer

I suspect these failed to update during one of the many 1 click updates I've done to the site over the years.

I want to get these right now. Can anyone suggest correct SQL query to re-assign to the now default ID's without mangling anything.

Thanks

Baz