Extract array of JSONs to columns in SQL - sql

Question

I have the following table with JSON collections:
ID
SliderJson
1
[{"Slider":11, "Value":2},{"Slider":4, "Value":3}]
2
3
[{"Slider":11, "Value":4},{"Slider":4, "Value":3},{"Slider":25, "Value":3},{"Slider":2, "Value":4},{"Slider":5, "Value":3}]
As can be see in the example not all records have a value, and those that have the length of the array vary (by a maximum of 9 items).
Ideally I would like to create a column for each slider that contains its entry value, but there are about 400 million records and about 80 different sliders.
So I would be happy to create a columns only for certain sliders, say 4 and 5 and get the following table.
ID
SliderJson
4
5
1
[{"Slider":11, "Value":2},{"Slider":4, "Value":3}]
3
NULL
2
NULL
NULL
3
[{"Slider":11, "Value":4},{"Slider":4, "Value":3},{"Slider":25, "Value":3},{"Slider":2, "Value":4},{"Slider":5, "Value":3}]
3
3
Or alternatively create a table that will extract the json to the columns in the following way:
ID
SliderJson
slider1
value1
slider2
value2
slider3
value3
1
[{"Slider":11, "Value":2},{"Slider":4, "Value":3}]
11
2
4
3
NULL
NULL
2
NULL
NULL
NULL
NULL
NULL
NULL
3
[{"Slider":11, "Value":4},{"Slider":4, "Value":3},{"Slider":25, "Value":3},{"Slider":2, "Value":4},{"Slider":5, "Value":3}]
11
4
4
3
25
3
Both options are good and working for me, the only consideration is efficiency because as mentioned there are a millions of records (and maybe there are other options that are preferred and I have not thought about).
It also important that each record be associated with its original id.
So far I tried the following proceeder, however even when I execute it on very small amount of rows (only 100) it took hours, so I guess something wrong.
DECLARE #NOTE_ID uniqueidentifier
DECLARE #USER_ID uniqueidentifier
DECLARE #SINGEL_SLIDER NVARCHAR(MAX)
DECLARE SLIDER_CURSOR CURSOR FOR SELECT [NoteID],[UserID],[SliderJSON] FROM [dbo].[SmallData]
OPEN SLIDER_CURSOR
FETCH NEXT FROM SLIDER_CURSOR INTO #NOTE_ID, #USER_ID, #SINGEL_SLIDER
WHILE ##FETCH_STATUS = 0
BEGIN
IF len(#SINGEL_SLIDER)>1
BEGIN
IF OBJECT_ID('tempdb..#TMP') IS NOT NULL
DROP TABLE #TMP
SELECT *
INTO #TMP
FROM OPENJSON(#SINGEL_SLIDER)
DECLARE #SLIDER_VALUE NVARCHAR(MAX)
DECLARE SLIDER_VALUE_CURSOR CURSOR FOR SELECT [value] FROM #TMP
OPEN SLIDER_VALUE_CURSOR
FETCH NEXT FROM SLIDER_VALUE_CURSOR INTO #SLIDER_VALUE
WHILE ##FETCH_STATUS = 0
BEGIN
IF OBJECT_ID('tempdb..#TMP1') IS NOT NULL
DROP TABLE #TMP1
SELECT *
INTO #TMP1
FROM OPENJSON(#SLIDER_VALUE)
DECLARE #SLIDER_ID NVARCHAR(100)
DECLARE #SLIDER_OPTION_ID NVARCHAR(100)
SET #SLIDER_ID = (SELECT [value] FROM #TMP1 WHERE [key] = 'Slider')
SET #SLIDER_OPTION_ID = (SELECT [value] FROM #TMP1 WHERE [key] = 'Value')
IF #SLIDER_ID = 4
BEGIN
UPDATE [dbo].[SmallData]
SET [4] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 7
BEGIN
UPDATE [dbo].[SmallData]
SET [7] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 1
BEGIN
UPDATE [dbo].[SmallData]
SET [1] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 10
BEGIN
UPDATE [dbo].[SmallData]
SET [10] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 43
BEGIN
UPDATE [dbo].[SmallData]
SET [43] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 15
BEGIN
UPDATE [dbo].[SmallData]
SET [15] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
ELSE IF #SLIDER_ID = 18
BEGIN
UPDATE [dbo].[SmallData]
SET [18] = #SLIDER_OPTION_ID
WHERE [NoteID] = #NOTE_ID
END
END
FETCH NEXT FROM SLIDER_VALUE_CURSOR INTO #SLIDER_VALUE
END
CLOSE SLIDER_VALUE_CURSOR
DEALLOCATE SLIDER_VALUE_CURSOR
FETCH NEXT FROM SLIDER_CURSOR INTO #NOTE_ID, #USER_ID, #SINGEL_SLIDER
END
CLOSE SLIDER_CURSOR
DEALLOCATE SLIDER_CURSOR
I would appreciate any help on this subject.

Answer 1

I'm unsure why you thought you needed all those cursors and a temp table, they are unnecessary.
You need two OPENJSONs here. To get just the value for each slider, you can just pivot on the slider number.
SELECT
s.*,
j.*
FROM dbo.SmallData s
CROSS APPLY (
SELECT
pvt.*
FROM (
SELECT
j2.Slider,
j2.Value
FROM OPENJSON (s.SliderJSON) j1
CROSS APPLY OPENJSON (j1.value)
WITH (Slider int, Value int) j2
) j
PIVOT (
MIN(Value) FOR Slider IN
([4],[5])
) pvt
) j;
Your second version can also be done pretty simply with a multi-column pivot.
SELECT
s.*,
j.*
FROM dbo.SmallData s
CROSS APPLY (
SELECT
MAX(CASE WHEN j1.[key] = '0' THEN j2.Slider END) slider1,
MAX(CASE WHEN j1.[key] = '0' THEN j2.Value END) value1,
MAX(CASE WHEN j1.[key] = '1' THEN j2.Slider END) slider2,
MAX(CASE WHEN j1.[key] = '1' THEN j2.Value END) value2,
MAX(CASE WHEN j1.[key] = '2' THEN j2.Slider END) slider3,
MAX(CASE WHEN j1.[key] = '2' THEN j2.Value END) value3,
MAX(CASE WHEN j1.[key] = '3' THEN j2.Slider END) slider4,
MAX(CASE WHEN j1.[key] = '3' THEN j2.Value END) value4,
MAX(CASE WHEN j1.[key] = '4' THEN j2.Slider END) slider5,
MAX(CASE WHEN j1.[key] = '4' THEN j2.Value END) value5,
MAX(CASE WHEN j1.[key] = '5' THEN j2.Slider END) slider6,
MAX(CASE WHEN j1.[key] = '5' THEN j2.Value END) value6,
MAX(CASE WHEN j1.[key] = '6' THEN j2.Slider END) slider7,
MAX(CASE WHEN j1.[key] = '6' THEN j2.Value END) value7,
MAX(CASE WHEN j1.[key] = '7' THEN j2.Slider END) slider8,
MAX(CASE WHEN j1.[key] = '7' THEN j2.Value END) value8,
MAX(CASE WHEN j1.[key] = '8' THEN j2.Slider END) slider9,
MAX(CASE WHEN j1.[key] = '8' THEN j2.Value END) value9
FROM OPENJSON (s.SliderJSON) j1
CROSS APPLY OPENJSON (j1.value)
WITH (Slider int, Value int) j2
) j;