I think one of the things that sets TCC apart from other integration engines is the ability to utilize pretty much any Oracle SQL function by using the customFunction feature. You simply declare the function you would like to use in the name attribute.
I ran across a situation where I needed to use the GREATEST function on two fields and was able to declare that function and pass the parameters exactly as you would if you were writing it in SQL developer as seen below.
<quer:filtering xmlns:quer="http://www.taleo.com/ws/integration/query"> <quer:lrd> <quer:customFunction name="GREATEST"> <quer:field path="Process,Steps,EndDate"/> <quer:field path="ProfileInformation,Application,CSWLatestDate"/> </quer:customFunction> </quer:lrd> </quer:filtering>