SQL Server - Change JSON string value to array - json

Question

I have a SQL Server Table with a JSON column. In it, I have a property 'Code' that contained a string with one value. Now, I want that 'Code' to be an Array to be able to contain more than one strings.
How can I update all my table values to change the property to an array?
"Code" : null --> "Code" : []
"Code" : "XX" --> "Code" : ["XX"]

Answer 1

You may try to modify the stored JSON as text using OPENJSON() with default schema to get the type of the $.Code part:
Sample data:
SELECT *
INTO Data
FROM (VALUES
(CONVERT(nvarchar(max), N'{"Code": "XX"}')),
(CONVERT(nvarchar(max), N'{"Code": null}')),
(CONVERT(nvarchar(max), N'{"Code": 1}')),
(CONVERT(nvarchar(max), N'{"Code": []}')),
(CONVERT(nvarchar(max), N'{"Code": {}}'))
) d (JsonColumn)
Statement:
UPDATE d
SET JsonColumn = JSON_MODIFY(
JsonColumn,
'$.Code',
JSON_QUERY(CONCAT('[', j.[value], ']'))
)
FROM Data d
OUTER APPLY (
SELECT
CASE
WHEN [type] = 0 THEN ''
WHEN [type] = 1 THEN CONCAT('"', STRING_ESCAPE([value], 'json'), '"')
WHEN [type] = 2 THEN [value]
ELSE '"not a scalar value"'
END AS [value]
FROM OPENJSON(d.JsonColumn, '$')
WHERE [key] = 'Code'
) j
Result:
JsonColumn
--------------------------------
{"Code": ["XX"]}
{"Code": []}
{"Code": [1]}
{"Code": ["not a scalar value"]}
{"Code": ["not a scalar value"]}
You may consider the #JeroenMostert's comment and use something like this:
UPDATE d
SET JsonColumn = JSON_MODIFY(
JsonColumn,
'$.Code',
JSON_QUERY(CONCAT('[', j.[value], ']'))
)
FROM Data d
OUTER APPLY (
SELECT IIF ([type] = 1, CONCAT('"', STRING_ESCAPE([value], 'json'), '"'), [value]) AS [value]
FROM OPENJSON(d.JsonColumn, '$')
WHERE [key] = 'Code'
) j