How to join JSON to update multiple rows by primary key - sql-server

Question

I am trying to update a log with JSON in SQL Server 2017. I can update a data point with json_value, which covers a few cases, but would ultimately like to join in incoming JSON.
Sample table:
key | col_1 | col_2 | col_3
----+-------------------------------+---------------|-----------------
1 | json.lines[0].data.meta.data | json.lines[0] | json.header.note
2 | json.lines[1].data.meta.data} | json.lines[1] | json.header.note
3 | json.lines[2].data.meta.data} | json.lines[2] | json.header.note
I'd like to update a single property in col_1 and update col_2 with an object as as as string.
Sample JSON:
declare #json nvarchar(max) = '[{
header: {
note: 'some note'
}, lines: [{
data {
id: {
key: 0,
name: 'item_1'
},
meta: {
data: 'item_1_data'
}
}, {...}, {...}
}]
}]'
Query:
update logTable set
col_1 = json_value(#json,'$.lines[__index__].data.meta.data'), -- what would the syntax for __index__ be?
col_2 = j.lines[key], -- pseudo code
col_3 = json_value(#json, '$'.header.note')
inner join openjson(#json) j
on json_value(#json,'$.line[?].id.key') = logTable..key -- ? denotes indices that I'd like to iterate = join over
Expected Output:
key | col_1 | col_2 | col_3
----+---------------+----------------------------|---------
1 | 'item_1_data' | 'data: { id: { key: 0...}' | '{header: { note: ...} }'
2 | 'item_2_data' | 'data: { id: { key: 1...}' | '{header: { note: ...} }'
3 | 'item_3_data' | 'data: { id: { key: 2...}' | '{header: { note: ...} }'
I'm not sure how to handle iterating over the $.line indices, but think a join would solve this if properly implemented.
How can I join to arrays of objects to update SQL rows by primary key?

Answer 1

Original answer:
You may try to parse your JSON using OPENJSON with explicit schema (note, that your JSON is not valid):
Table and JSON:
CREATE TABLE #Data (
[key] int,
col_1 nvarchar(100),
col_2 nvarchar(max)
)
INSERT INTO #Data
([key], [col_1], [col_2])
VALUES
(1, N'', N''),
(2, N'', N''),
(3, N'', N'')
DECLARE #json nvarchar(max) = N'[{
"lines": [
{
"data": {
"id": {
"key": 1,
"name": "item_1"
},
"meta": {
"data": "item_1_data"
}
}
},
{
"data": {
"id": {
"key": 2,
"name": "item_2"
},
"meta": {
"data": "item_2_data"
}
}
},
{
"data": {
"id": {
"key": 3,
"name": "item_3"
},
"meta": {
"data": "item_3_data"
}
}
}
]
}]'
Statement:
UPDATE #Data
SET
col_1 = j.metadata,
col_2 = j.data
FROM #Data
INNER JOIN (
SELECT *
FROM OPENJSON(#json, '$[0].lines') WITH (
[key] int '$.data.id.key',
metadata nvarchar(100) '$.data.meta.data',
data nvarchar(max) '$' AS JSON
)
) j ON #Data.[key] = j.[key]
Update:
Header is common for all rows, so use JSON_QUERY() to update the table:
Table and JSON:
CREATE TABLE #Data (
[key] int,
col_1 nvarchar(100),
col_2 nvarchar(max),
col_3 nvarchar(max)
)
INSERT INTO #Data
([key], col_1, col_2, col_3)
VALUES
(1, N'', N'', N''),
(2, N'', N'', N''),
(3, N'', N'', N'')
DECLARE #json nvarchar(max) = N'[{
"header": {
"note": "some note"
},
"lines": [
{
"data": {
"id": {
"key": 1,
"name": "item_1"
},
"meta": {
"data": "item_1_data"
}
}
},
{
"data": {
"id": {
"key": 2,
"name": "item_2"
},
"meta": {
"data": "item_2_data"
}
}
},
{
"data": {
"id": {
"key": 3,
"name": "item_3"
},
"meta": {
"data": "item_3_data"
}
}
}
]
}]'
Statement:
UPDATE #Data
SET
col_1 = j.metadata,
col_2 = j.data,
col_3 = JSON_QUERY(#json, '$[0].header')
FROM #Data
INNER JOIN (
SELECT *
FROM OPENJSON(#json, '$[0].lines') WITH (
[key] int '$.data.id.key',
metadata nvarchar(100) '$.data.meta.data',
data nvarchar(max) '$' AS JSON
)
) j ON #Data.[key] = j.[key]