Append Row To Each Group in SQL - sql

Question

Let's say that I have database table:
| id | value | rank |
| -----------|-----------|-------------|
| 303 | D | 3 |
| 404 | A | 1 |
| 505 | B | 1 |
| 505 | D | 4 |
| 202 | B | 1 |
| 505 | A | 5 |
| 303 | N | 2 |
| 101 | A | 1 |
| 505 | A | 7 |
| 202 | A | 6 |
| 202 | N | 3 |
| 505 | N | 3 |
| 202 | A | 4 |
| 505 | A | 2 |
| 202 | N | 5 |
| 303 | A | 1 |
| 505 | N | 6 |
| 202 | A | 2 |
Following:
SELECT *
FROM table_name
GROUP BY id
ORDER BY rank;
I get:
| id | value | rank |
| -----------|-----------|-------------|
| 101 | A | 1 |
| 202 | B | 1 |
| 202 | A | 2 |
| 202 | N | 3 |
| 202 | A | 4 |
| 202 | N | 5 |
| 202 | A | 6 |
| 303 | A | 1 |
| 303 | N | 2 |
| 303 | D | 3 |
| 404 | A | 1 |
| 505 | B | 1 |
| 505 | A | 2 |
| 505 | N | 3 |
| 505 | D | 4 |
| 505 | A | 5 |
| 505 | N | 6 |
| 505 | A | 7 |
However, for each group, I'd like to append an additional row with the value column taken from the id column so that the resulting table looks like:
| id | value | rank |
| -----------|-----------|-------------|
| 101 | A | 1 |
| 101 | 101 | 2 |
| 202 | B | 1 |
| 202 | A | 2 |
| 202 | N | 3 |
| 202 | A | 4 |
| 202 | N | 5 |
| 202 | A | 6 |
| 202 | 202 | 7 |
| 303 | A | 1 |
| 303 | N | 2 |
| 303 | D | 3 |
| 303 | 303 | 4 |
| 404 | A | 1 |
| 404 | 404 | 2 |
| 505 | B | 1 |
| 505 | A | 2 |
| 505 | N | 3 |
| 505 | D | 4 |
| 505 | A | 5 |
| 505 | N | 6 |
| 505 | A | 7 |
| 505 | 505 | 8 |
What is ANSI SQL (or most database agnostic) way to accomplish this?

Answer 1

You don't want a group by in the initial set as you appear to want all the rows back:
select "id", "value", "rank"
from T
union all
select "id", cast("id" as varchar(10)), max("rank") + 1
from T
group by "id"
order by "id", "rank";
And you can do this with grouping sets for the fun of it:
select "id",
grouping("rank"),
case when grouping("rank") = 0 then min("value") else cast("id" as varchar(10)) end as "value",
case when grouping("rank") = 0 then "rank" else max("rank") over (partition by "id") + 1 end as "rank"
from T
group by grouping sets ("id", "rank"), ("id")
order by "id", "rank";

Answer 2

Here's how I would do it:
SELECT id,
value,
rank
FROM table_name
UNION
SELECT id,
id AS value,
max(rank) + 1 AS rank
FROM table_name
GROUP BY id
ORDER BY id, rank;

Answer 3

You seem to want:
select id, value, max(rank) as rank
from t
group by id, value
union all
select id, id, max(rank) + 1
from t
group by id;