Creating Custom SQL Queries

I'm stuggling to implement a filter on a custom query and have found this thread.

However,

I think is no longer the case. I've got test results showing when NOT putting in quotes.

BUT, I just can't get it to work.

In my WHERE clause I have

project1_registrations.registrations.regEmail LIKE :P2

and in my Parameters I have

Name
:P2

Expression
{{$_GET.filter}}

Test Value
&amy%

It gives me Query Results as expected but isn't working on the page. I'm fairly sure it's down to the % symbols not being there but I've tried putting them in just about every possible place and nothing is working.