Help with transform

Hi,

We currently have a field where the users select an expiry date and this gets entered into the database as yyyy-MM-dd 00:00:00.

Ideally we’d want that to be yyyy-MM-dd 23:59:59.

I’m thinking this should be done using a transform but I’m having trouble making it work. Could anyone give me a quick step-by-step on creating a transform like this?

Thanks,
Nick.