'%+%' <- function(x,y) paste(x,y,sep="")

y<-"y1"
x<-"somethingorother"
query<-
'SELECT DISTINCT x AS ' %+% x %+%',\n'    %+%
'                y AS ' %+% y %+% '\n'    %+%
' FROM tbl
 WHERE id=%s
 AND num=%d'

cat(query,"\n")

收益率：

> cat(query,"\n")
SELECT DISTINCT x AS somethingorother,y AS y1
 FROM tbl
 WHERE id=%s
 AND num=%d