Problem with select statement for duplicate data

Hi All

        I am trying to runt he following select statement on a table in order search for duplicate rows in the table

                select column1,column2,column3,count() from table group by column1,column2,column3 having count() > 1;

        This however gives me the following error:

                ERROR: count(*) must be used to call a parameterless aggregate function


        Does anybody know what the correct statement or syntax is in postgres in order to run the same type of query?


            I need to go through 974 tables to look for duplicate rows in all the tables, however struggling to get this command right.

Regards
Machiel