Boyum selected row syntax on more than one row

Hi all,

I want to use the special row syntax to total up a field on selected rows. Of course, there is no issue showing the value for just 1 selected row, what i want to know is if i can select more than one row and then do a SUM of another field using that special row syntax. Something like;

SQL(SELECT SUM($[$BOY_1.WorkTime.0]) WHERE $[$BOY_1.Date.0] = $[$BOY_1.Date.0.SELECTED])

If i try and do this with it just gives me the value of the first selected row. Does anyone know if this is achievable without using a line loop?