Add Sequential Letter column to table

In C I can switch between int and char to build a list of sequential integers and then convert them to ASCII characters that will be sequential according to the alphabet.

Is there a way to do this in postgres to get a column with row values “A”,”B”,”C” etc…?

the only way I can think of would be to start with a SERIAL column of ints and then write a CASE to set each row individually. The Tables big enough that it would be much preferred to do this automatically somehow.

Answer

Take a look here: Calculate MS Excel column name from its number in PostgreSQL

CREATE FUNCTION excel_column(col integer)
  RETURNS text AS
$BODY$
WITH RECURSIVE t(n, out) AS (
    SELECT col/26-(col%26=0)::int, chr((col-1)%26 + 65)
  UNION ALL
    SELECT n/26-(n%26=0)::int, chr((n-1)%26 + 65) || out FROM t
    where n>0
)
SELECT out FROM t where n=0;
$BODY$
  LANGUAGE sql IMMUTABLE LEAKPROOF STRICT;

Usage:

select excel_column(x) from generate_series(1,800) x;

Result:

A
B
..
AA
AB
..
ZZ
AAA
..
ADT