Yeah, the other way is more general: create, then join to a temporary table. (that floor() was just a first try, I should have removed it)
insert into $t values (394, 2, '*Inserted 1st*', :insert_location);
-- update $t set f_sort = floor(f_sort)+1 where f_sort >= :insert_loca
+tion; -- meh
-- instead:
-- create temporary table
create temp table _t as
select f_node_id, f_sort, row_number() over () as new_number
from (
select f_node_id, f_sort
from $t
order by f_sort
) as f
order by new_number ;
-- update table
update $t t set f_sort = _t.new_number
from _t
where _t.f_node_id = t.f_node_id --> join expression
and _t.new_number <> t.f_sort --> avoid unnecessary writes
;
drop table _t; --> remove temp table
It's verbose-ugly but it works without repeating the values.