JSON Oracle SQL parsing / unnest embedded JSON data in escaped form - json

Question

Here is my JSON stored in a CLOB column:
select upJSON from myLocations;
{"values":[
{"nameValuePairs":{"upJSON":"{\"mResults\":[0.0,0.0],\"mProvider\":\"fused\",\"mDistance\":0.0,\"mAltitude\":0.0}","id":"1","updated":"2015-03-30 20:28:51"}},
{"nameValuePairs":{"upJSON":"{\"mResults\":[0.0,0.0],\"mProvider\":\"FINDME\",\"mDistance\":0.0,\"mAltitude\":22.2}","id":"2","updated":"2015-03-30 20:28:53"}},
{"nameValuePairs":{"upJSON":"{\"mResults\":[0.0,0.0],\"mProvider\":\"fused\",\"mDistance\":0.0,\"mAltitude\":0.0}","id":"3","updated":"2015-03-30 20:28:55"}},
{"nameValuePairs":{"upJSON":"{\"mResults\":[0.0,0.0],\"mProvider\":\"fused\",\"mDistance\":0.0,\"mAltitude\":0.0}","id":"4","updated":"2015-03-30 20:28:57"}}
]}
(I have inserted newlines for clarity)
Please: What is the SQL (or PL/SQL) needed to select just the value of mProvider, mAltitude, and the id from the 2nd "nameValuePairs"
(= "FINDME" and 22.2 and "2") in the example above)
??

Answer 1

Since you're using 12c you have access to the native JSON parsing (as long as your CLOB column has an is json check constraint).
Some good background is available at:
https://docs.oracle.com/database/121/ADXDB/json.htm#ADXDB6371
If you're JSON looks something like this:
{
"values": [
{
"nameValuePairs": {
"upJSON": {
"mResults": [
"0.0",
"0.0"
],
"mProvider": "fused",
"mDistance": "0.0",
"mAltitude": "22.2"
},
"id": "1",
"updated": "2015-03-30 20:28:51"
}
},
...
...
Although, when I put your snippet from the question into JSONLint it returns:
{
"values": [
{
"nameValuePairs": {
"upJSON": "{\"mResults\":[0.0,0.0],\"mProvider\":\"fused\",\"mDistance\":0.0,\"mAltitude\":0.0}",
"id": "1",
"updated": "2015-03-30 20:28:51"
}
},
{
"nameValuePairs": {
"upJSON": "{\"mResults\":[0.0,0.0],\"mProvider\":\"FINDME\",\"mDistance\":0.0,\"mAltitude\":22.2}",
"id": "2",
"updated": "2015-03-30 20:28:53"
}
},
Something like the following might get you started:
select
upJSON.values
from
myLocations
where
json_value(upJSON, '$nameValuePairs.id' returning varchar2 error on error) = '2';
If you want to limit the query to a single ID, you'll need to add a full-text or function-based index to the JSON column.

Answer 2

https://odieweblog.wordpress.com/2015/04/12/json_table-chaining/#comment-1025
with tmp as (
SELECT /*+ no_merge */ d.*
FROM ulocations ul,
json_table(ul.upjson, '$'
columns(
NESTED PATH '$.values[*].nameValuePairs'
COLUMNS (
updated VARCHAR2(19 CHAR) PATH '$.updated'
, id varchar2(9 char) path '$._id'
, upJSON VARCHAR2(2000 CHAR) PATH '$.upJSON'
)) ) d
--where d.id = '0'
)
select t.updated
, t.id
, jt2.*
from tmp t
, json_table(t.upJSON, '$'
columns mProvider varchar2(5) path '$.mProvider'
, mLongitude number path '$.mLongitude'
) jt2
;