Inserting a constant along with field values.

Hi all,

I'm pondering an issue which has arisen.

Suppose  I have a query of the type:

SELECT
                x.f1,
                x.f2,
                ..
                x.fn,
                y.f1,
                y.f2,
                 ..
                 y.fn,
                 COUNT(z.id)
FROM xtab x
JOIN ytab y ON x.x_key = y.y_key
JOIN ztab z ON z.z_key = y._other_key

Now, what I would like to do is to put the COUNT(z.id) into a CTE and
then essentially SELECT a constant value into that part of the query

WITH cte AS
(
  SELECT COUNT(z.id) AS zcnt FROM z
)
SELECT
              x.fields,
              y.fields,
              c.zcnt
FROM xtab x JOIN ytab y ON  x.x_key = y.y_key
JOIN cte c ON .......

And it's here that I'm stuck. I just can't figure out how to get the
constant  value into the result set.

I keep getting messages like "unknown column 'p.pcnt'".

Any ideas, references &c appreciated!

TIA and g