Contacts list ABC

DROP TABLE IF EXISTS contacts;
CREATE TEMP TABLE contacts
  as
    select *
    from (
           VALUES
             (1::int, 'abc'::VARCHAR),
             (2::int, 'Aac'::VARCHAR),
             (3::int, 'bvC'::VARCHAR),
             (4::int, 'Bvc'::VARCHAR),
             (5::int, 'Avc'::VARCHAR),
             (6::int, 'BV'::VARCHAR),
             (7::int, 'FR'::VARCHAR),
             (8::int, 'dddD'::VARCHAR),
             (9::int, 'WWW'::VARCHAR),
             (10::int, 'WWW'::VARCHAR),
             (11::int, 'WWW'::VARCHAR),
             (12::int, 'WWW'::VARCHAR),
             (13::int, 'WWW'::VARCHAR),
             (14::int, 'WWW'::VARCHAR),
             (15::int, 'WWW'::VARCHAR),
             (16::int, 'WWW'::VARCHAR),
             (17::int, 'WWW'::VARCHAR)
         ) as t (id, name);
SELECT * FROM generate_series(ascii('A'), ascii('Z'));
-- SELECT * FROM generate_series(ascii('A'), ascii('Z')) ABC GROUP BY ABC
select ascii('A');
select chr(65);
select substring('Abc' from 1 for 1);
select upper('a');
SELECT ABC, array_agg(contacts.* ORDER BY contacts.name, contacts.id)
FROM generate_series(ascii('A'), ascii('Z')) AS ABC INNER JOIN contacts
    ON ascii(upper(substring(contacts.name FROM 1 FOR 1))) = ABC
GROUP BY ABC
ORDER BY ABC ASC;
-- PAGINATION
SELECT ABC, json_agg(contacts.*)
FROM generate_series(ascii('A'), ascii('Z')) AS ABC INNER JOIN (SELECT contacts.* from contacts ORDER BY contacts.name, contacts.id LIMIT 3 OFFSET 1) as contacts
    ON ascii(upper(substring(contacts.name FROM 1 FOR 1))) = ABC
GROUP BY ABC
ORDER BY ABC ASC;
-- coalesce
SELECT ABC, coalesce(json_agg(contacts.*) FILTER (WHERE contacts.name NOTNULL), '{}')
FROM generate_series(ascii('A'), ascii('Z')) AS ABC LEFT JOIN (SELECT contacts.* from contacts ORDER BY contacts.name, contacts.id LIMIT 3 OFFSET 1) as contacts
    ON ascii(upper(substring(contacts.name FROM 1 FOR 1))) = ABC
GROUP BY ABC
ORDER BY ABC ASC;