Referring to http://golang.org/src/pkg/database/sql/sql.go

func (s *Stmt) Exec(args ...interface{}) (line 663) checks for
si.(driver.ColumnConverter) to convert args to subtypes.  

However, a very similar function: func (s *Stmt) Query(args ...interface{}) (line 796)
does not check to see if the statement implements driver.ColumnConvert.  According to
the documentation, it looks like the Exec function is correct and that the Query
function should be updated.