You can do that using an UPDATE statement after you added the new column.

I am assuming you have a primary key column named pk_column in your table. Obviously you need to replace that with the actual primary key column in your table.

update the_table
   set id_int = t.rn
from (
  select pk_column, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.pk_column = t.pk_column;

If you really have a table without a primary key (why?), you can use the built-in ctid instead:

update the_table
   set id_int = t.rn
from (
  select ctid as id_, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.ctid = t.id_;

To add the new column use:

ALTER TABLE the_table ADD COLUMN id_int integer;

To populate the new column you need an UPDATE statement.

I am assuming you have a primary key column named pk_column in your table. Obviously you need to replace that with the actual primary key column in your table.

update the_table
   set id_int = t.rn
from (
  select pk_column, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.pk_column = t.pk_column;

If you really have a table without a primary key (why?), you can use the built-in ctid instead:

update the_table
   set id_int = t.rn
from (
  select ctid as id_, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.ctid = t.id_;

You can do that using an UPDATE statement after you added the new column.

I am assuming you have a primary key column named pk_column in your table. Obviously you need to replace that with the actual primary key column in your table.

update the_table
   set id_int = t.rn
from (
  select pk_column, 
         row_number() over (partition by id_string) as rn
  from the_table
) t
where the_table.pk_column = t.pk_column;

You can do that using an UPDATE statement after you added the new column.

I am assuming you have a primary key column named pk_column in your table. Obviously you need to replace that with the actual primary key column in your table.

update the_table
   set id_int = t.rn
from (
  select pk_column, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.pk_column = t.pk_column;

If you really have a table without a primary key (why?), you can use the built-in ctid instead:

update the_table
   set id_int = t.rn
from (
  select ctid as id_, 
         dense_rank() over (order by id_string) as rn
  from the_table
) t
where the_table.ctid = t.id_;