SQL Server 2017

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Microsoft SQL Server 2017 (RTM-CU21) (KB4557397) - 14.0.3335.7 (X64) 
	Jun 12 2020 20:39:00 
	Copyright (C) 2017 Microsoft Corporation
	Express Edition (64-bit) on Windows Server 2019 Standard 10.0 <X64> (Build 17763: ) (Hypervisor)



CREATE TABLE my_table (
  id INTEGER,
  Level1 VARCHAR(2),
  Level2 VARCHAR(2),
  Level3 INTEGER
);

INSERT INTO my_table
  (id, Level1, Level2, Level3)
VALUES
  ('1', 'US', 'CA', '13000'),
  ('2', 'FR', 'PA', '30000'),
  ('3', 'US', 'CA', '24000'),
  ('4', 'US', 'LA', '10000'),
  ('5', 'UK', 'LN', '500'),
  ('6', 'UK', 'LN', '600'),
  ('7', 'FR', 'PA', '888'),
  ('8', 'FR', 'DF', '1000');
8 rows affected

SELECT
    Level1,
    Level2,
    SUM(Level3) as Level3
FROM
    my_table
GROUP BY
    Level1,
    Level2;
    
SELECT
    Level1,
    STRING_AGG(Level2,',') as Level2,
    STRING_AGG(Level3,',') as Level3
FROM (
    SELECT
        Level1,
        Level2,
        SUM(Level3) as Level3
    FROM
        my_table
    GROUP BY
        Level1,
        Level2
) t
GROUP BY
    Level1


Level1
Level2
Level3


US
CA
37000

FR
DF
1000

US
LA
10000

UK
LN
1100

FR
PA
30888




Level1
Level2
Level3


FR
DF,PA
1000,30888

UK
LN
1100

US
CA,LA
37000,10000