Capture The ID Of The Last Record Entered And Use In An Update

I'm entering a Selection record for a partiuclar lotID,  

Once entered, I need to obtain its SelectionID then use it to update a another field within that record.

Here's what I've been doing...

--insert values into a testchangeorders table

INSERT INTO testchangeorders VALUES (2,3,3,3,1,'red',0,5)

--Find the SelectionsID of the last record created for that partiuclar LotID

SELECT MAX (SelectionsID)

FROM testchangeorders

WHERE LotID = 2

--Once located, I was trying to update a field called uniqueID with a contantination of '3-' & the record's SelectionsID

UPDATE testchangeorders

SET UniqueID = ('3-' & SelectionID

WHERE SelectionsID = SELECT MAX (SelectionsID) AND LotID = 2)