MySQL 8.0

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CREATE TABLE test  -- 22 records
(
  the_word TEXT,
  no_of_times INTEGER
);

INSERT INTO test VALUES ('keyword1',  100);
INSERT INTO test VALUES ('keyword2',  90);
INSERT INTO test VALUES ('keyword3',  80);
INSERT INTO test VALUES ('keyword4',  70);
INSERT INTO test VALUES ('keyword5',  60);
INSERT INTO test VALUES ('keyword6',  50);
INSERT INTO test VALUES ('keyword7',  40);
INSERT INTO test VALUES ('keyword8',  40);
INSERT INTO test VALUES ('keyword9',  40);
INSERT INTO test VALUES ('keyword10', 40);
INSERT INTO test VALUES ('keyword11', 40);
INSERT INTO test VALUES ('keyword12', 40);
INSERT INTO test VALUES ('keyword13', 40);
INSERT INTO test VALUES ('keyword14', 40);
INSERT INTO test VALUES ('keyword15', 40);
INSERT INTO test VALUES ('keyword16', 40);
INSERT INTO test VALUES ('keyword17', 40);
INSERT INTO test VALUES ('keyword18', 40);
INSERT INTO test VALUES ('keyword19', 40);
INSERT INTO test VALUES ('keyword20', 40);
INSERT INTO test VALUES ('keyword21', 40);
INSERT INTO test VALUES ('keyword22', 40);

WITH cte1 AS
(
  SELECT 15 AS tot_num_recs_wanted  -- the 15 could come from a table
),
cte2 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY no_of_times DESC) AS rn
  FROM test
)
SELECT * FROM cte2;


the_word
no_of_times
rn


keyword1
100
1

keyword2
90
2

keyword3
80
3

keyword4
70
4

keyword5
60
5

keyword6
50
6

keyword7
40
7

keyword8
40
8

keyword9
40
9

keyword10
40
10

keyword11
40
11

keyword12
40
12

keyword13
40
13

keyword14
40
14

keyword15
40
15

keyword16
40
16

keyword17
40
17

keyword18
40
18

keyword19
40
19

keyword20
40
20

keyword21
40
21

keyword22
40
22


WITH cte1 AS
(
  SELECT 15 AS tot_num_recs_wanted  -- the 15 could come from a table
),
cte2 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY no_of_times DESC) AS rn
  FROM test
  -- putting LIMIT 1 OFFSET (SELECT tot_num_recs_wanted 
  -- FROM cte1) here would have made life easier - it would
  -- have eliminated the need for cte3 and the ROW_NUMBER() construct
),
cte3 AS
(
  SELECT rn, no_of_times nt
  FROM cte2
  WHERE rn = (SELECT tot_num_recs_wanted FROM cte1)
)
SELECT * FROM cte3;


rn
nt


15
40


WITH cte1 AS
(
  SELECT 15 AS tot_num_recs_wanted  -- the 15 could come from a table
),
cte2 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY no_of_times DESC) AS rn
  FROM test
),
cte3 AS
(
  SELECT rn, no_of_times nt
  FROM cte2
  WHERE rn = (SELECT tot_num_recs_wanted FROM cte1)
),
cte4 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY RAND()) AS rand_rn
    FROM test
  WHERE no_of_times = (SELECT nt FROM cte3) -- i.e. 40
)
SELECT * FROM cte4;


the_word
no_of_times
rand_rn


keyword8
40
1

keyword19
40
2

keyword11
40
3

keyword21
40
4

keyword18
40
5

keyword10
40
6

keyword17
40
7

keyword9
40
8

keyword16
40
9

keyword12
40
10

keyword20
40
11

keyword13
40
12

keyword15
40
13

keyword14
40
14

keyword7
40
15

keyword22
40
16


WITH cte1 AS
(
  SELECT 15 AS tot_num_recs_wanted  -- the 15 could come from a table
),
cte2 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY no_of_times DESC) AS rn
  FROM test
),
cte3 AS
(
  SELECT rn, no_of_times nt
  FROM cte2
  WHERE rn = (SELECT tot_num_recs_wanted FROM cte1)
),
cte4 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY RAND()) AS rand_rn
    FROM test
  WHERE no_of_times = (SELECT nt FROM cte3)
), cte5 AS
(
  SELECT * FROM cte4
  WHERE rand_rn <= (SELECT tot_num_recs_wanted FROM cte1) 
               - (SELECT COUNT(*) FROM test WHERE no_of_times > (SELECT nt FROM cte3))
)
SELECT * FROM cte5;


the_word
no_of_times
rand_rn


keyword15
40
1

keyword18
40
2

keyword22
40
3

keyword10
40
4

keyword7
40
5

keyword21
40
6

keyword14
40
7

keyword16
40
8

keyword12
40
9


WITH cte1 AS
(
  SELECT 15 AS tot_num_recs_wanted  -- the 15 could come from a table
),
cte2 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY no_of_times DESC) AS rn
  FROM test
),
cte3 AS
(
  SELECT rn, no_of_times nt
  FROM cte2
  WHERE rn = (SELECT tot_num_recs_wanted FROM cte1)
),
cte4 AS
(
  SELECT 
    *,
    ROW_NUMBER() OVER (ORDER BY RAND()) AS rand_rn
    FROM test
  WHERE no_of_times = (SELECT nt FROM cte3)
), cte5 AS
(
  SELECT * FROM cte4
  WHERE rand_rn <= (SELECT tot_num_recs_wanted FROM cte1) 
               - (SELECT COUNT(*) FROM test WHERE no_of_times > (SELECT nt FROM cte3))
)
SELECT the_word, no_of_times FROM cte5
UNION 
SELECT the_word, no_of_times FROM test
WHERE no_of_times > (SELECT nt FROM cte3)
ORDER BY no_of_times DESC;


the_word
no_of_times


keyword1
100

keyword2
90

keyword3
80

keyword4
70

keyword5
60

keyword6
50

keyword19
40

keyword16
40

keyword20
40

keyword17
40

keyword18
40

keyword9
40

keyword15
40

keyword12
40

keyword8
40
the_word	no_of_times	rn
keyword1	100	1
keyword2	90	2
keyword3	80	3
keyword4	70	4
keyword5	60	5
keyword6	50	6
keyword7	40	7
keyword8	40	8
keyword9	40	9
keyword10	40	10
keyword11	40	11
keyword12	40	12
keyword13	40	13
keyword14	40	14
keyword15	40	15
keyword16	40	16
keyword17	40	17
keyword18	40	18
keyword19	40	19
keyword20	40	20
keyword21	40	21
keyword22	40	22