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DECLARE @a int = 752 , @b nvarchar(max) = '[4,4]';
SELECT
@a AS a,
(
SELECT '[' + STRING_AGG(value, ',') + ']'
FROM (
SELECT DISTINCT value
FROM OPENJSON(@b) AS j
) j
) AS b;
| a | b |
|---|---|
| 752 | [4] |