create or replace function public.get_pk_name(table_name name) returns varchar as $$
declare
        stmt                     varchar;
        pk_column_name  varchar;
begin

        stmt :=    'select kc.column_name '
                || ' from information_schema.table_constraints tc'
                ....

        if stmt is not null then execute stmt into pk_column_name; end if;

        return pk_column_name;

end; $$ language 'plpgsql'; 

create or replace function public.mark_as_deleted() returns trigger as $$
declare
        stmt                     varchar;
        pk_column_name  varchar;
        pk_value               integer;
begin

        stmt :=    'select public.get_pk_name(' 
                || ''''
                || TG_TABLE_NAME 
                || ''''
                || ');';

        if stmt is not null then execute stmt into pk_column_name; end if;

        if pk_column_name is not null then      
                stmt :=    'update public.'
                        || quote_ident(TG_TABLE_NAME)
                        || ' set deleted_when = now() ,deleted_by = '
                        || ''''
                        || current_user
                        || ''''
                        || ' where "'
                        || pk_column_name
                        || '" = '
                        || old.pk_column_name  <--------------------------------------------------------------------------------------------
                        || ';'; 

                if stmt is not null then execute stmt; end if;
        end if;
end;
end; $$ language 'plpgsql'; 

if [ $# -ne 2 ]
then
        echo "usage : $0 database_name schema_name"
        exit
fi
database_name=$1
schema_name=$2

psql -qAt $database_name <<EOF

set search_path to $schema_name;
---------------------------------------------------------------------------------------------------------------------------------------------
-- create db objects
---------------------------------------------------------------------------------------------------------------------------------------------
drop table if exists audit_history;
create table audit_history (
...


---------------------------------------------------------------------------------------------------------------------------------------------
-- generic function for all triggers
---------------------------------------------------------------------------------------------------------------------------------------------
create or replace function populate_audit_history() returns trigger as $$
begin
...

psql -qAt $database_name <<'EOF'

set search_path to $schema_name;

\copy (select * from audit_history) to audit_history.csv with csv;

\copy sync.audit_history(id_audit_history ,table_name ,operation ,audit_id ,user_name ,insertion_date)  from 'audit_history.csv';

psql:.work/_import_modifs.sql:1: ERROR:  invalid input syntax for integer: "1,tblContacts,DELETE,1,rubin,2017-02-08 11:56:41.979212"
CONTEXT:  COPY audit_history, line 1, column id_audit_history: "1,tblContacts,DELETE,1,rubin,2017-02-08 11:56:41.979212"

1,tblContacts,DELETE,1,rubin,2017-02-08 11:56:41.979212

---------------------------------------------------------------------------------------------------------------------------------------------
-- create db objects
---------------------------------------------------------------------------------------------------------------------------------------------
drop table if exists record_tracking;
create table record_tracking (
	 id_record_tracking	serial	
	,table_name		varchar
	,operation		varchar
	,pk_value		varchar
	,user_name		varchar
	,insertion_date		timestamp 	default now()
);

drop sequence if exists record_tracking_seq;
create sequence record_tracking_seq;

drop table if exists app_table;
create table app_table (
	 pk	integer		primary	key
	,info	varchar
);


---------------------------------------------------------------------------------------------------------------------------------------------
-- generic functions for triggers
---------------------------------------------------------------------------------------------------------------------------------------------

create or replace function get_pk_value(this_table_name name) returns varchar as $$
declare
	pk_column_name	varchar;
begin
	select
		c.column_name
	into
		pk_column_name
	from
		information_schema.table_constraints		tc 
	join 
		information_schema.constraint_column_usage	ccu 
	using 
		(constraint_schema, constraint_name) 
	join 
		information_schema.columns			c 
	on 	
		c.table_schema = tc.constraint_schema 
	and 	
		tc.table_name = c.table_name 
	and 	
		ccu.column_name = c.column_name
	where 
		constraint_type = 'PRIMARY KEY' 
	and 
		tc.table_name = this_table_name;

	return pk_column_name;
end;
$$ language 'plpgsql'; 


create or replace function record_tracking() returns trigger as $$
declare
	pk_column_name	varchar;
	pk_value	varchar;
begin

	select get_pk_value(TG_TABLE_NAME) into pk_column_name;
	pk_value := old.pk_column_name; <------------------------------------------------------------------- Horreur !

	insert into record_tracking
		(table_name, operation, pk_value_type, user_name)
	values 
		(TG_TABLE_NAME, TG_OP, pk_value, current_user);
	return new;
end; 
$$ language 'plpgsql'; 


---------------------------------------------------------------------------------------------------------------------------------------------
-- create after insert trigger
---------------------------------------------------------------------------------------------------------------------------------------------
create trigger trg_app_table_record_tracking after insert or update or delete on app_table 
	for each row execute procedure record_tracking();