Using functions with EXPRESSION

[Sergey Miltchakov]

Hello! 

I have a 'mydate' and 'the_geom' fields in my table and want to color the
shapes on my layer depending on the year of the 'mydate' value. What
expression do I use in order to do that? Is it possible to use postgre
'date_part' function at all?

I tried several ways but none helped me. It just returns blank image
(without the layer). Other expressions work fine.

Regards,
Sergey