MySQL 8.0

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CREATE Table ranking (GameRank  INt,global_sales  INT);
INSERT INTO `ranking` VALUES(0,200),(0,300),(0,250),(0,125)
SELECT * FROM ranking


GameRank
global_sales


0
200

0
300

0
250

0
125


SET @ranking = 0
UPDATE ranking r 
INNER JOIN (SELECT @ranking := @ranking + 1 _rank, global_sales FROM ranking ORDER BY global_sales DESC) t  ON  r.global_sales = t.global_sales
  SET GameRank = _rank
SELECT * FROM ranking   OrDER By global_sales DESC


GameRank
global_sales


1
300

2
250

3
200

4
125


UPDATE ranking r 
INNER JOIN (SELECT global_sales,RANK() OVER (  ORDER BY global_sales DESC ) my_rank FROM ranking) t  
ON  r.global_sales = t.global_sales
  SET GameRank = my_rank
SELECT * FROM ranking   OrDER By global_sales DESC


GameRank
global_sales


1
300

2
250

3
200

4
125