MySQL 5.7

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CREATE TABLE table_1 (
  `category` VARCHAR(2),
  `user_id` INT(2), 
  `value` DECIMAL(3,2)
 );
INSERT INTO table_1
(`category`, `user_id`, `value`)
VALUES
('A', 1, 0.01),
('A', 2, 0.05),
('B', 4, 0.34),
('B', 7, 0.27)
;
Create view new_tableview as
SELECT t1.`category`, t1.`user_id`, t1.`value`, t2.minid - t1.`value` as new_value FROM table_1 t1 JOIN 
( SELECT `category`,MIN(`user_id`) minid FROM table_1 GROUP BY `category`) t2 ON t1.`category` = t2.`category`
SELECT * FROM new_tableview


category
user_id
value
new_value


A
1
0.01
0.99

A
2
0.05
0.95

B
4
0.34
3.66

B
7
0.27
3.73