Group all rows after nth row together - mysql

Question

I have the current table:
+----------+-------+
| salesman | sales |
+----------+-------+
| 1 | 142 |
| 2 | 120 |
| 3 | 176 |
| 4 | 140 |
| 5 | 113 |
| 6 | 137 |
| 7 | 152 |
+----------+-------+
I would like to make a query to retrieve the 3 top salesman, and an "Other" column, that would be the sum of everyone else. The expected output would be:
+----------+-------+
| salesman | sales |
+----------+-------+
| 3 | 176 |
| 7 | 152 |
| 1 | 142 |
| Others | 510 |
+----------+-------+
I am using MySQL, and I am experienced about it, but i can't imagine a way of doing this kind of GROUP BY.
A tried UNION with 2 SELECT, one for the top 3 salesman and another select for the "Others", but I couldn't figure a way of excluding the top 3 from the 2nd SELECT

Answer 1

You can do this by LEFT JOINing your table to a list of the top 3 salesmen, and then grouping on the COALESCEd salesman number from the top 3 table (which will be NULL if the salesman is not in the top 3).
SELECT COALESCE(top.sman, 'Others') AS saleman,
SUM(sales) AS sales
FROM test
LEFT JOIN (SELECT salesman AS sman
FROM test
ORDER BY sales DESC
LIMIT 3) top ON top.sman = test.salesman
GROUP BY saleman
ORDER BY saleman = 'Others', sales DESC
Output:
saleman sales
3 176
7 152
1 142
Others 510
Demo on dbfiddle

Answer 2

Using UNION, ORDER BY, LIMIT, OFFSET AND GROUP BY statements you should do the trick:
SELECT salesman, sales
FROM t
ORDER BY sales DESC LIMIT 3
UNION
SELECT 'Others', SUM(sales)
FROM (SELECT salesman, sales
FROM t
ORDER BY sales DESC LIMIT 3, 18446744073709551615) AS tt;
The big number at the end is the way to apply limit until the end of the table, as suggested here

Answer 3

This is a pain in MySQL:
(select salesman, count(*) as cnt
from t
group by salesman
order by count(*), salesman
limit 3
) union all
(select 'Others', count(*)
from t left join
(select salesman, count(*) as cnt
from t
group by salesman
order by count(*)
limit 3
) t3
on t3.salesman = t.salesman
where t3.salesman is null
);

Answer 4

This should be the fastest one if appropriate indexes are present:
(
SELECT salesman, sales
FROM t
ORDER BY sales DESC
LIMIT 3
)
UNION ALL
(
SELECT 'Other', SUM(sales) - (
SELECT SUM(sales)
FROM (
SELECT sales
FROM t
ORDER BY sales DESC
LIMIT 3
) AS top3
)
FROM t
)
ORDER BY CASE WHEN salesman = 'Other' THEN NULL ELSE sales END DESC

Answer 5

this will work:
select salesman,sales from tablename a where a.salesman in (3,7,1)
union all
select 'others' as others,sum(a.sales) as sum_of_others from tablename a where
a.salesman not in (3,7,1) group by others;
check https://www.db-fiddle.com/f/73GjFXL3KsZsYnN26g3rS2/0