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CREATE TABLE t (tx_id int, trade_id int);
INSERT INTO t (tx_id, trade_id) VALUES
(100,11),
(99,11),
(98,11),
(97,10),
(96,10),
(95,9),
(94,9),
(93,8);
SET @ngroups=2;
WITH dat
AS
(
SELECT tx_id, trade_id, DENSE_RANK() OVER (ORDER BY trade_id DESC) AS trade_id_rank
FROM t
)
SELECT tx_id, trade_id
FROM dat
WHERE trade_id_rank <= @ngroups;
| tx_id | trade_id |
|---|---|
| 100 | 11 |
| 99 | 11 |
| 98 | 11 |
| 97 | 10 |
| 96 | 10 |