MySQL 8.0

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CREATE TABLE YourTable
    (`_ID` int, `weight_date` bigint, `weight_start_week` decimal(10,2), `weight_end_week` decimal(10,2))
;
    
INSERT INTO YourTable
    (`_ID`, `weight_date`, `weight_start_week`, `weight_end_week`)
VALUES
    (52, 1636675200, 4.30, 4.30),
    (53, 1637280000, 4.60, 7.10),
    (54, 1637884800, 4.55, 4.05),
    (55, 1638489600, 4.90, 4.60),
    (56, 1639094400, 3.20, 8.25),
    (57, 1639699200, 4.75, 7.80),
    (58, 1640131200, 4.50, 4.70),
    (59, 1640908800, 6.05, 5.75),
    (60, 1641513600, 6.30, 6.60),
    (61, 1642118400, 8.70, 7.00),
    (62, 1642723200, 3.50, 3.60),
    (63, 1643328000, 8.20, 3.85)
;
SELECT FROM_UNIXTIME(weight_date)
       , t.*
       , t.weight_start_week + t.weight_end_week AS Total
FROM   YourTable t
ORDER BY weight_date DESC


FROM_UNIXTIME(weight_date)
_ID
weight_date
weight_start_week
weight_end_week
Total


2022-01-28 00:00:00
63
1643328000
8.20
3.85
12.05

2022-01-21 00:00:00
62
1642723200
3.50
3.60
7.10

2022-01-14 00:00:00
61
1642118400
8.70
7.00
15.70

2022-01-07 00:00:00
60
1641513600
6.30
6.60
12.90

2021-12-31 00:00:00
59
1640908800
6.05
5.75
11.80

2021-12-22 00:00:00
58
1640131200
4.50
4.70
9.20

2021-12-17 00:00:00
57
1639699200
4.75
7.80
12.55

2021-12-10 00:00:00
56
1639094400
3.20
8.25
11.45

2021-12-03 00:00:00
55
1638489600
4.90
4.60
9.50

2021-11-26 00:00:00
54
1637884800
4.55
4.05
8.60

2021-11-19 00:00:00
53
1637280000
4.60
7.10
11.70

2021-11-12 00:00:00
52
1636675200
4.30
4.30
8.60


    SELECT *
           , LEAD(total_weight, 1) OVER(
               ORDER BY weight_date DESC
           ) AS prev_total_weight
           , LEAD(weight_date, 1) OVER(
               ORDER BY weight_date DESC
           ) AS prev_total_weight_date
    
           , MIN(total_weight) OVER() AS lowest_weight
           , MAX(total_weight) OVER() AS highest_weight
 
         
           , FROM_UNIXTIME(weight_date, '%u') AS weight_week
           , FIRST_VALUE(weight_date) OVER (ORDER BY total_weight DESC, weight_date DESC) AS highest_weight_date
           , ROW_NUMBER() OVER(
              ORDER BY weight_date DESC
           ) AS RowNum
           
       

             

    FROM   (
              SELECT *, weight_start_week + weight_end_week AS total_weight
              FROM   YourTable
           ) t
    ORDER BY RowNum


_ID
weight_date
weight_start_week
weight_end_week
total_weight
prev_total_weight
prev_total_weight_date
lowest_weight
highest_weight
weight_week
highest_weight_date
RowNum


63
1643328000
8.20
3.85
12.05
7.10
1642723200
7.10
15.70
04
1642118400
1

62
1642723200
3.50
3.60
7.10
15.70
1642118400
7.10
15.70
03
1642118400
2

61
1642118400
8.70
7.00
15.70
12.90
1641513600
7.10
15.70
02
1642118400
3

60
1641513600
6.30
6.60
12.90
11.80
1640908800
7.10
15.70
01
1642118400
4

59
1640908800
6.05
5.75
11.80
9.20
1640131200
7.10
15.70
52
1642118400
5

58
1640131200
4.50
4.70
9.20
12.55
1639699200
7.10
15.70
51
1642118400
6

57
1639699200
4.75
7.80
12.55
11.45
1639094400
7.10
15.70
50
1642118400
7

56
1639094400
3.20
8.25
11.45
9.50
1638489600
7.10
15.70
49
1642118400
8

55
1638489600
4.90
4.60
9.50
8.60
1637884800
7.10
15.70
48
1642118400
9

54
1637884800
4.55
4.05
8.60
11.70
1637280000
7.10
15.70
47
1642118400
10

53
1637280000
4.60
7.10
11.70
8.60
1636675200
7.10
15.70
46
1642118400
11

52
1636675200
4.30
4.30
8.60
null
null
7.10
15.70
45
1642118400
12

FROM_UNIXTIME(weight_date)	_ID	weight_date	weight_start_week	weight_end_week	Total
2022-01-28 00:00:00	63	1643328000	8.20	3.85	12.05
2022-01-21 00:00:00	62	1642723200	3.50	3.60	7.10
2022-01-14 00:00:00	61	1642118400	8.70	7.00	15.70
2022-01-07 00:00:00	60	1641513600	6.30	6.60	12.90
2021-12-31 00:00:00	59	1640908800	6.05	5.75	11.80
2021-12-22 00:00:00	58	1640131200	4.50	4.70	9.20
2021-12-17 00:00:00	57	1639699200	4.75	7.80	12.55
2021-12-10 00:00:00	56	1639094400	3.20	8.25	11.45
2021-12-03 00:00:00	55	1638489600	4.90	4.60	9.50
2021-11-26 00:00:00	54	1637884800	4.55	4.05	8.60
2021-11-19 00:00:00	53	1637280000	4.60	7.10	11.70
2021-11-12 00:00:00	52	1636675200	4.30	4.30	8.60