Insert an object into a JSON array in SQL Server - sql

Question

Every example that I've seen for JSON_MODIFY shows inserting a simple value such as a string into an array.
Suppose I have the following JSON stored in my SQL Server column:
[{"id": 1, "name": "One"}, {"id": 2, "name": "Two"}]
How do I append {"id": 3, "name": "Three"} to it?
When I try using JSON_MODIFY as shown below, a string is inserted:
UPDATE TheTable SET TheJSON = JSON_MODIFY(TheJSON, 'append $', N'{"id": 3, "name": "Three"}') WHERE Condition = 1;
Here is the resulting value for TheJSON column:
[{"id": 1, "name": "One"}, {"id": 2, "name": "Two"}, "{\"id\":3, \"name\": \"Three\"}"]
Other Attempts:
I noticed that I can create the JSON string that I want like this:
SELECT json.*
FROM TheTable t
CROSS APPLY OPENJSON(t.TheJSON) WITH (
id int N'$.id',
name nvarchar(100) N'$.name'
)
UNION ALL
SELECT 3 as id, N'Three' as name
FOR JSON AUTO;
However, when I go to try and use it in an update statement, it doesn't work:
UPDATE TheTable
SET TheJSON = (
SELECT json.* FROM TheTable t
CROSS APPLY OPENJSON(t.TheJSON) WITH (
id int N'$.id',
name nvarchar(100) N'$.name'
) as json
UNION ALL -- NO ERROR (and no update) when I remove UNION ALL+SELECT
SELECT 3 as id, N'Three' as name
FOR JSON AUTO
);
I get the following error:
Msg 1086, Level 15, State 1, Line 1: The FOR XML and FOR JSON clauses are invalid in views, inline functions, derived tables, and subqueries when they contain a set operator. To work around, wrap the SELECT containing a set operator using derived table or common table expression or view and apply FOR XML or FOR JSON on top of it.

Answer 1

You should wrap the third parameter of your JSON_MODIFY statement with JSON_QUERY():
UPDATE TheTable
SET TheJSON = JSON_MODIFY(TheJSON, 'append $', JSON_QUERY(N'{"id": 3, "name": "Three"}'))
WHERE Condition = 1;
Here is a complete sample:
DECLARE #TheTable table(TheJSON nvarchar(max), Condition int )
DECLARE #mystring nvarchar(100)='{"id": 3, "name": "Three"}'
INSERT INTO #TheTable SELECT '[{"id": 1, "name": "One"}, {"id": 2, "name": "Two"}]', 1
UPDATE #TheTable
SET TheJSON = JSON_MODIFY(TheJSON, 'append $', JSON_QUERY(N'{"id": 3, "name": "Three"}'))
WHERE Condition = 1;
SELECT TheJSON FROM #TheTable
This is the final output:
[{"id": 1, "name": "One"}, {"id": 2, "name": "Two"},{"id": 3, "name": "Three"}]
More info on JSON_QUERY here, and the explanation of the issue is here.