SQL Server 2022

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CREATE TABLE MyTable (
  ID INTEGER,
  UserID INTEGER,
  RecordedTransaction VARCHAR(8),
  RecordedAmount DECIMAL(10,2)
);

INSERT INTO MyTable
  (ID, UserID, RecordedTransaction, RecordedAmount)
VALUES
  ('1', '12345678', 'Purchase', '0.10'),
  ('2', '12345678', 'Deposit', '100.00'),
  ('3', '12345678', 'Purchase', '100.00'),
  ('4', '12345678', 'Deposit', '30.00'),
  ('5', '12345678', 'Purchase', '30.00'),
  ('6', '12345678', 'Deposit', '25.00'),
  ('7', '12345678', 'Purchase', '0.80');
7 rows affected

 UPDATE a 
 SET a.RecordedAmount = 
   case when RecordedTransaction = 'Deposit' THEN FLOOR(RAND(CHECKSUM(NEWID())) * (20 - 10 + 1) + 10) 
 ELSE 
 (CAST(RAND(CHECKSUM(NEWID())) * 
 (CASE WHEN  RecordedAmount < 0.99 THEN RecordedAmount ELSE 0.99 END) AS FLOAT) + 0.01 )
  end
 FROM dbo.MyTable a
7 rows affected

SELECT * fROM MyTable


ID
UserID
RecordedTransaction
RecordedAmount


1
12345678
Purchase
0.02

2
12345678
Deposit
10.00

3
12345678
Purchase
0.41

4
12345678
Deposit
16.00

5
12345678
Purchase
0.98

6
12345678
Deposit
11.00

7
12345678
Purchase
0.56

ID	UserID	RecordedTransaction	RecordedAmount
1	12345678	Purchase	0.02
2	12345678	Deposit	10.00
3	12345678	Purchase	0.41
4	12345678	Deposit	16.00
5	12345678	Purchase	0.98
6	12345678	Deposit	11.00
7	12345678	Purchase	0.56