SQL Server 2019

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CREATE TABLE HashTable(
    RecordID    INT,
    GroupIdentifier    INT,
    Hash               VARCHAR(50),
    GroupHashList      VARCHAR(150)
);
INSERT INTO HashTable VALUES
(1,1, '73F294873462B2BA0E930FD16DCCB7', NULL),
(2,1, '90E749375DF806CB6E3F5CA48FFA38', NULL),
(3,1, 'E44256CE7CFCB971EB679BAC25A697', NULL),
(4,2, '73F294873462B2BA0E930FD16DCCB7', NULL),
(5,2, 'E44256CE7CFCB971EB679BAC25A697', NULL),
(6,2, '90E749375DF806CB6E3F5CA48FFA38', NULL);

SELECT * FROM HashTable;


RecordID
GroupIdentifier
Hash
GroupHashList


1
1
73F294873462B2BA0E930FD16DCCB7
null

2
1
90E749375DF806CB6E3F5CA48FFA38
null

3
1
E44256CE7CFCB971EB679BAC25A697
null

4
2
73F294873462B2BA0E930FD16DCCB7
null

5
2
E44256CE7CFCB971EB679BAC25A697
null

6
2
90E749375DF806CB6E3F5CA48FFA38
null


SELECT STRING_AGG([Hash],';') WITHIN GROUP (ORDER BY [Hash] ASC)
FROM HashTable
GROUP BY [GroupIdentifier]


(No column name)


73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697

73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697


UPDATE HashTable
SET GroupHashList = c.HashList
FROM HashTable INNER JOIN (SELECT (STRING_AGG([Hash],';') WITHIN GROUP (ORDER BY [Hash] ASC)) AS [HashList],
    [GroupIdentifier]
    FROM HashTable
    GROUP BY [GroupIdentifier]) c
    ON c.[GroupIdentifier] = HashTable.[GroupIdentifier];

SELECT * FROM HashTable


RecordID
GroupIdentifier
Hash
GroupHashList


1
1
73F294873462B2BA0E930FD16DCCB7
73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697

2
1
90E749375DF806CB6E3F5CA48FFA38
73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697

3
1
E44256CE7CFCB971EB679BAC25A697
73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697

4
2
73F294873462B2BA0E930FD16DCCB7
73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38

5
2
E44256CE7CFCB971EB679BAC25A697
73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38

6
2
90E749375DF806CB6E3F5CA48FFA38
73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38

RecordID	GroupIdentifier	Hash	GroupHashList
1	1	73F294873462B2BA0E930FD16DCCB7	null
2	1	90E749375DF806CB6E3F5CA48FFA38	null
3	1	E44256CE7CFCB971EB679BAC25A697	null
4	2	73F294873462B2BA0E930FD16DCCB7	null
5	2	E44256CE7CFCB971EB679BAC25A697	null
6	2	90E749375DF806CB6E3F5CA48FFA38	null

RecordID	GroupIdentifier	Hash	GroupHashList
1	1	73F294873462B2BA0E930FD16DCCB7	73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697
2	1	90E749375DF806CB6E3F5CA48FFA38	73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697
3	1	E44256CE7CFCB971EB679BAC25A697	73F294873462B2BA0E930FD16DCCB7;90E749375DF806CB6E3F5CA48FFA38;E44256CE7CFCB971EB679BAC25A697
4	2	73F294873462B2BA0E930FD16DCCB7	73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38
5	2	E44256CE7CFCB971EB679BAC25A697	73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38
6	2	90E749375DF806CB6E3F5CA48FFA38	73F294873462B2BA0E930FD16DCCB7;E44256CE7CFCB971EB679BAC25A697;90E749375DF806CB6E3F5CA48FFA38