Getting the sum of Counts in the same query

I am trying to get the sum of all the counts of this field.

SELECT FieldName, 
       COUNT(*) AS count,
       SUM(COUNT(*)) AS sum
FROM TABLE
GROUP BY FieldName

But when I add the SUM, I get this error:

"Cannot perform an aggregate function on an expression containing an aggregate or a subquery"

Surely there is a way to get the total count in its own field?

>Solution :

Usually, this may be counted by window function, where window – whole table.

SELECT FieldName, 
       COUNT(*) AS count,
       SUM(COUNT(*))over() AS sum
FROM test
GROUP BY FieldName

fiddle