Related
I am attempting to extract from my json object
hits = [{“title”: “Facebook”,
“domain”: “facebook.com”},
{“title”: “Linkedin”,
“domain”: “linkedin.com”}]
When I use:
json_extract(hits,'$.title') as title,
nothing is returned. I would like the result to be: [Facebook, Linkedin].
However, when I extract by a scalar value, ex.:
json_extract_scalar(hits,'$[0].title') as title,
it works and Facebook is returned.
hits contains a lot of values, so I need to use json_extract in order to get all of them, so I can't do each scalar individually. Any suggestions to fix this would be greatly appreciated.
I get INVALID_FUNCTION_ARGUMENT: Invalid JSON path: '$.title' as an error for $.title (double stars). When I try unnest I get INVALID_FUNCTION_ARGUMENT: Cannot unnest type: varchar as an error and INVALID_FUNCTION_ARGUMENT: Cannot unnest type: json. I get SYNTAX_ERROR: line 26:19: Column '$.title' cannot be resolved when I try double quotes
Correct json path to exract all titles is $.[*].title (or $.*.title), though it is not supported by athena. One option is to cast your json to array of json and use transform on it:
WITH dataset AS (
SELECT * FROM (VALUES
(JSON '[{"title": "Facebook",
"domain": "facebook.com"},
{"title": "Linkedin",
"domain": "linkedin.com"}]')
) AS t (json_string))
SELECT transform(cast(json_string as ARRAY(JSON)), js -> json_extract_scalar(js, '$.title'))
FROM dataset
Output:
_col0
[Facebook, Linkedin]
Fits you have an array. So $.title doesn't exist see below
Second, you have not a valid json, is must have double quotes " like the example shows
SET #a := '[{
"title": "Facebook",
"domain": "facebook.com"
},
{
"title": "Linkedin",
"domain": "linkedin.com"
}
]'
SELECT json_extract(#a,'$[0]') as title
| title |
| :---------------------------------------------- |
| {"title": "Facebook", "domain": "facebook.com"} |
SELECT JSON_EXTRACT(#a, "$[0].title") AS 'from'
| from |
| :--------- |
| "Facebook" |
SELECT #a
| #a |
| :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [{<br> "title": "Facebook",<br> "domain": "facebook.com"<br> },<br> {<br><br> "title": "Linkedin",<br> "domain": "linkedin.com"<br> }<br>] |
db<>fiddle here
Consider this table:
DROP TABLE IF EXISTS `example`;
CREATE TABLE `example` (
`id` int NOT NULL AUTO_INCREMENT,
`content` json NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;
And these rows:
INSERT INTO example(content)
VALUES (
'[ { "date": "1617210148", "name": "John", "status": "0" },
{ "date": "1617210148", "name": "Jack", "status": "0" },
{ "date": "1617210148", "name": "Henry", "status": "0" }]'
);
I'd like to update the value of the key status where name = Jack to 1
The result would be:
{ "date": "1617210148", "name": "Jack", "status": "1" }
How can I do this using JSON_REPLACE() or JSON_SET() in a SQL query (I'm aiming for a partial update since I'm using MySQL 8.0.25)?
This is very awkward, nearly impossible with MySQL's JSON functions.
You can use JSON_REPLACE() or JSON_SET(), but both require that you know the path to the field you want to change. So in this case, we can see that the array element is $[1] but if you didn't know that, you couldn't use this solution.
mysql> select json_pretty(json_replace(content, '$[1].status', '1')) as j
from example\G
*************************** 1. row ***************************
j: [
{
"date": "1617210148",
"name": "John",
"status": "0"
},
{
"date": "1617210148",
"name": "Jack",
"status": "1"
},
{
"date": "1617210148",
"name": "Henry",
"status": "0"
}
]
The question like yours has come up before on Stack Overflow, for example JSON update single value in MySQL table. The solution in that case depends on you knowing which array element your pseudo-record exists in.
You can get the path to a JSON element with JSON_SEARCH(), but you can only search by value, not by a key/value pair. If "Jack" occurs in some other field, that would also be found.
mysql> select json_unquote(json_search(content, 'one', 'Jack')) as path from example;
+-----------+
| path |
+-----------+
| $[1].name |
+-----------+
To search for a key/value pair, you need to use JSON_TABLE() and that requires you upgrade to MySQL 8.0. And that doesn't tell you the path to the element, it only allows you to return a specific row out of the array.
mysql> select j.* from example cross join json_table(content, '$[*]' columns(
date int unsigned path '$.date',
name varchar(10) path '$.name',
status int path '$.status')
) as j where name = 'Jack';
+------------+------+--------+
| date | name | status |
+------------+------+--------+
| 1617210148 | Jack | 0 |
+------------+------+--------+
Here's a trick: You can extract the name field, and that turns into an array of those values:
mysql> select json_extract(content, '$[*].name') as a from example;
+---------------------------+
| a |
+---------------------------+
| ["John", "Jack", "Henry"] |
+---------------------------+
Then you can search that array to get the array position:
mysql> select json_search(json_extract(content, '$[*].name'), 'one', 'Jack') as root from example;
+--------+
| root |
+--------+
| "$[1]" |
+--------+
Some unquoting and adding .status and you can get the full path to the field you want to update:
mysql> select concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status') as path from example;
+-------------+
| path |
+-------------+
| $[1].status |
+-------------+
Now use it in a JSON_SET() call:
mysql> select json_pretty(
json_set(content,
concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status'),
'1')) as newcontent
from example\G
*************************** 1. row ***************************
newcontent: [
{
"date": "1617210148",
"name": "John",
"status": "0"
},
{
"date": "1617210148",
"name": "Jack",
"status": "1"
},
{
"date": "1617210148",
"name": "Henry",
"status": "0"
}
]
Using this in an UPDATE looks like this:
mysql> update example set content = json_set(content, concat(json_unquote(json_search(json_extract(content, '$[*].name'), 'one', 'Jack')), '.status'), '1');
That's a long way to go. Now compare how difficult that is to:
UPDATE content SET status = 1 WHERE name = 'Jack';
Storing data in a JSON document when you eventually want to use SQL expressions to search or update individual fields within the JSON document is a costly mistake. It increases the complexity of any code you write to do it, and the developer who needs to take over maintenance of your code after you have moved on to another project will curse your name.
I have a column which contains a JSON value of different lengths
["The Cherries:2.50","Draw:3.25","Swansea Jacks:2.87"]
I want to split them and store into a JSON like so:
[
{
name: "The Cherries",
odds: 2.50
},
{
name: "Draw",
odds: 3.25
},
{
name: "Swansea",
odds: 2.87
},
]
What I did right now is looping and splitting them in the UI which to me is quite heavy for the client. I want to parse and split them all in a single query.
If you are running MySQL 8.0, you can use json_table() to split the original arrayto rows, and then build new objects and aggregate them with json_arrayagg().
We need a primary key column (or set of columns) so we can properly aggreate the generated rows, I assumed id:
select
t.id,
json_arrayagg(json_object(
'name', substring(j.val, 1, locate(':', j.val) - 1),
'odds', substring(j.val, locate(':', j.val) + 1)
)) new_js
from mytable t
cross join json_table(t.js, '$[*]' columns (val varchar(500) path '$')) as j
group by t.id
Demo on DB Fiddle
Sample data:
id | js
-: | :-------------------------------------------------------
1 | ["The Cherries:2.50", "Draw:3.25", "Swansea Jacks:2.87"]
Query results:
id | new_js
-: | :----------------------------------------------------------------------------------------------------------------------
1 | [{"name": "The Cherries", "odds": "2.50"}, {"name": "Draw", "odds": "3.25"}, {"name": "Swansea Jacks", "odds": "2.87"}]
You can use json_table to create rows from the json object.
Just replace table_name with your table name and json with the column that contains json
SELECT json_arrayagg(json_object('name',SUBSTRING_INDEX(person, ':', 1) ,'odds',SUBSTRING_INDEX(person, ':', -1) ))
FROM table_name,
JSON_TABLE(json, '$[*]' COLUMNS (person VARCHAR(40) PATH '$') people;
Here is a Db fiddle you can refer
https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=801de9f067e89a48d45ef9a5bd2d094a
I am using mssql and one column is having json data, I want to update that part of that json which is an array, by passing the id.
{
"customerName":"mohan",
"custId":"e35273d0-c002-11e9-8188-a1525f580dfd",
"feeds":[
{
"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e",
"feedName":"ccsdcdscsdc",
"format":"Excel",
"sources":[
{
"sourceId":69042417,
"name":"TV 2 Livsstil"
},
{
"sourceId":69042419,
"name":"Turk Max"
}
]
},
{
"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e",
"feedName":"dfgdfgdfgdfgsdfg",
"format":"XmlTV",
"sources":[
{
"sourceId":69042417,
"name":"TV 2 Livsstil"
},
{
"sourceId":69042419,
"name":"Turk Max"
}
]
}
]
}
suppose if I am going to pass customerId and feedId, it should update the whole feed with the feed which I have passed.
I tried with below query, but no help.
UPDATE
ExtractsConfiguration.dbo.Customers
SET
configJSON = JSON_MODIFY(configJSON,'$.feeds[]',{"feedName":"ccsdcdscsdc"})
WHERE
CustomerId = '9ee07040-c001-11e9-b29a-55eb3439cd7c'
AND json_query(configJSON,'$.feeds[].feedId'='57f221d0-c310-11e9-8af7-cf1cf42fc72e');
This, #mohan, is a tricky one and I took it on as a challenge to myself. There is a way to update a nested JSON object's value like you're asking, however, it's not as straight forward as it seems.
Because you're working within an array, you need the array's index in order to update a nested value. In your case you don't know the index within the array, however, you do have a key-value you can reference, in this case, your feedName.
In order to update your value, you first need to "unpack" your JSON so that you can filter for a specific feedName, "ccsdcdscsdc" in your example.
Here is an example that you can run in SSMS that will get you moving in the right direction.
The first thing I created was #Customers TABLE variable to mimic the data structure you showed in your example and inserted your sample data.
DECLARE #Customers TABLE ( CustomerId VARCHAR(50), configJSON VARCHAR(MAX) );
INSERT INTO #Customers ( CustomerID, configJSON ) VALUES ( '9ee07040-c001-11e9-b29a-55eb3439cd7c', '{"customerName":"mohan","custId":"e35273d0-c002-11e9-8188-a1525f580dfd","feeds":[{"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]},{"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e","feedName":"dfgdfgdfgdfgsdfg","format":"XmlTV","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]}]}' );
Running a SELECT against #Customers returns the following:
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| CustomerId | configJSON |
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 9ee07040-c001-11e9-b29a-55eb3439cd7c | {"customerName":"mohan","custId":"e35273d0-c002-11e9-8188-a1525f580dfd","feeds":[{"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]},{"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e","feedName":"dfgdfgdfgdfgsdfg","format":"XmlTV","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]}]} |
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
Next, I matched your rules for the update: Update a nested JSON value that is restricted to a specific CustomerId (9ee07040-c001-11e9-b29a-55eb3439cd7c) and a feedName (ccsdcdscsdc).
Like I mentioned, we need to "unpack" the JSON first because we don't know the specific key (index) value that should be updated. The easiest way to accomplish both tasks (unpack/update) is to use a Common Table Expression (CTE).
So, here's how I did that:
;WITH Config_CTE AS (
SELECT * FROM #Customers AS Customer
CROSS APPLY OPENJSON( configJSON, '$.feeds' ) AS Config
WHERE
Customer.CustomerId = '9ee07040-c001-11e9-b29a-55eb3439cd7c'
AND JSON_VALUE( Config.value, '$.feedName' ) = 'ccsdcdscsdc'
)
UPDATE Config_CTE
SET configJSON = JSON_MODIFY( configJSON, '$.feeds[' + Config_CTE.[key] + '].format', 'MS Excel' );
The CTE allows us to "unpack" (I made this word up as it seemed fitting) the JSON contained in configJSON, which then allows us to apply a filter against the feedName.
AND JSON_VALUE( Config.value, '$.feedName' ) = 'ccsdcdscsdc'
You'll also note that we included the CustomerId rule:
Customer.CustomerId = '9ee07040-c001-11e9-b29a-55eb3439cd7c'
Both the CustomerId and feedName could easily be SQL variables.
So, what did this do? If we were to look at Configs_CTE resultset ( by changing the UPDATE... to SELECT * FROM Config_CTE ) we would see:
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------+
| CustomerId | configJSON | key | value | type |
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------+
| 9ee07040-c001-11e9-b29a-55eb3439cd7c | {"customerName":"mohan","custId":"e35273d0-c002-11e9-8188-a1525f580dfd","feeds":[{"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]},{"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e","feedName":"dfgdfgdfgdfgsdfg","format":"XmlTV","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]}]} | 0 | {"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]} | 5 |
+--------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------+
There is a bunch of information here, but what we really care about is the "key" column as this contains the feed index ( in this case 0 ) that we want to update.
With that, was able to complete the request and UPDATE format from "Excel" to "MS Excel" for the "feed" with the feedName of "ccsdcdscsdc".
This guy ( note the use of Config_CTE.[key] ):
UPDATE Config_CTE
SET configJSON = JSON_MODIFY( configJSON, '$.feeds[' + Config_CTE.[key] + '].format', 'MS Excel' );
Did it work? Let's look at the updated table's data.
+--------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| CustomerId | configJSON |
+--------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 9ee07040-c001-11e9-b29a-55eb3439cd7c | {"customerName":"mohan","custId":"e35273d0-c002-11e9-8188-a1525f580dfd","feeds":[{"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"MS Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]},{"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e","feedName":"dfgdfgdfgdfgsdfg","format":"XmlTV","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]}]} |
+--------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
Here's the updated JSON "beautified" (pretty sure I didn't make up that one).
{
"customerName": "mohan",
"custId": "e35273d0-c002-11e9-8188-a1525f580dfd",
"feeds": [{
"feedId": "57f221d0-c310-11e9-8af7-cf1cf42fc72e",
"feedName": "ccsdcdscsdc",
"format": "MS Excel",
"sources": [{
"sourceId": 69042417,
"name": "TV 2 Livsstil"
}, {
"sourceId": 69042419,
"name": "Turk Max"
}]
}, {
"feedId": "59bbd360-c312-11e9-8af7-cf1cf42fc72e",
"feedName": "dfgdfgdfgdfgsdfg",
"format": "XmlTV",
"sources": [{
"sourceId": 69042417,
"name": "TV 2 Livsstil"
}, {
"sourceId": 69042419,
"name": "Turk Max"
}]
}]
}
Well, there you have it, format for feedName "ccsdcdscsdc" has been updated from "Excel" to "MS Excel". I was not clear on what you were trying to update, so I used format for my testing/example.
I hope this gets you moving in the right direction with your task. Happy coding!
Here's the complete example that can be run in SSMS:
-- CREATE A CUSTOMERS TABLE TO MIMIC SCHEMA --
DECLARE #Customers TABLE ( CustomerId VARCHAR(50), configJSON VARCHAR(MAX) );
INSERT INTO #Customers ( CustomerID, configJSON ) VALUES ( '9ee07040-c001-11e9-b29a-55eb3439cd7c', '{"customerName":"mohan","custId":"e35273d0-c002-11e9-8188-a1525f580dfd","feeds":[{"feedId":"57f221d0-c310-11e9-8af7-cf1cf42fc72e","feedName":"ccsdcdscsdc","format":"Excel","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]},{"feedId":"59bbd360-c312-11e9-8af7-cf1cf42fc72e","feedName":"dfgdfgdfgdfgsdfg","format":"XmlTV","sources":[{"sourceId":69042417,"name":"TV 2 Livsstil"},{"sourceId":69042419,"name":"Turk Max"}]}]}' );
-- SHOW CURRENT DATA --
SELECT * FROM #Customers;
-- UPDATE "format" FROM "Excel" to "MS Excel" FOR feedName: ccsdcdscsdc --
WITH Config_CTE AS (
SELECT * FROM #Customers AS Customer
CROSS APPLY OPENJSON( configJSON, '$.feeds' ) AS Config
WHERE
Customer.CustomerId = '9ee07040-c001-11e9-b29a-55eb3439cd7c'
AND JSON_VALUE( Config.value, '$.feedName' ) = 'ccsdcdscsdc'
)
UPDATE Config_CTE
SET configJSON = JSON_MODIFY( configJSON, '$.feeds[' + Config_CTE.[key] + '].format', 'MS Excel' );
-- SHOW UPDATED DATA --
SELECT * FROM #Customers;
EDIT:
i wanted to update the feed with the given feedId with the whole new
feed
To replace one "feed" with an entirely new feed, you may do the following:
-- REPLACE AN ENTIRE JSON ARRAY OBJECT --
DECLARE #MyNewJson NVARCHAR(MAX) = '{"feedId": "this_is_an_entirely_new_node","feedName": "ccsdcdscsdc","format": "NewFormat","sources": [{"sourceId": 1,"name": "New Source 1"},{"sourceId": 2,"name": "New Source 2"}]}';
WITH Config_CTE AS (
SELECT * FROM #Customers AS Customer
CROSS APPLY OPENJSON( configJSON, '$.feeds' ) AS Config
WHERE
Customer.CustomerId = '9ee07040-c001-11e9-b29a-55eb3439cd7c'
AND JSON_VALUE( Config.value, '$.feedName' ) = 'ccsdcdscsdc'
)
UPDATE Config_CTE
SET configJSON = JSON_MODIFY( configJSON, '$.feeds[' + Config_CTE.[key] + ']', JSON_QUERY( #MyNewJson ) );
After running this, the feeds now appear as:
{
"customerName": "mohan",
"custId": "e35273d0-c002-11e9-8188-a1525f580dfd",
"feeds": [
{
"feedId": "this_is_an_entirely_new_node",
"feedName": "ccsdcdscsdc",
"format": "NewFormat",
"sources": [
{
"sourceId": 1,
"name": "New Source 1"
},
{
"sourceId": 2,
"name": "New Source 2"
}
]
},
{
"feedId": "59bbd360-c312-11e9-8af7-cf1cf42fc72e",
"feedName": "dfgdfgdfgdfgsdfg",
"format": "XmlTV",
"sources": [
{
"sourceId": 69042417,
"name": "TV 2 Livsstil"
},
{
"sourceId": 69042419,
"name": "Turk Max"
}
]
}
]
}
Note the use of JSON_QUERY( #MyNewJson ) in the UPDATE. This is important.
From Microsoft's Docs:
JSON_QUERY without its optional second parameter returns only the
first argument as a result. Since JSON_QUERY always returns valid
JSON, FOR JSON knows that this result does not have to be escaped.
If you were to pass #MyNewJson without the JSON_QUERY your new json would be escaped ( e.g., "customerName" becomes \"customerName\" ) as if it were being stored as plain text. JSON_QUERY will return unescaped, valid JSON which is necessary in your case.
Also note that the only change I made to replace the entire feed vs. a single item value was switching
'$.feeds[' + Config_CTE.[key] + '].format'
to
'$.feeds[' + Config_CTE.[key] + ']'.
I am using postgres 9.5 and i have a table like this:
create table t1 (
id serial,
fkid int not null,
tstamp timestamp with time zone,
data jsonb
)
a typical json is:
{
"WifiStatistic": {
"Interfaces": {
"wlan0": {
"qualityLevel": {
"type": "graph",
"unit": "string",
"value": "75",
"graphDisplayName": "Quality level"
},
"SNR": {
"type": "graph",
"unit": "string",
"value": "75",
"graphDisplayName": "SNR"}
}
}
}
}
What 'id like as a result of a query that extract the quality level is a recordset like:
id | fkid | tstamp | value | graphdisplayName
-------------------------------------------------
1 | 1 | 2017-01-22 | 75 | "Quality Level"
what kind of query might i use?
Thanks to #VaoTsun for his comment, i ended up using this:
select
tstamp, id, fkid,
data->'WifiStatistics'->'Interfaces'->'wlan0'->'qualityLevel'->'value' as value,
data #>'{WifiStatistics, Interfaces, wlan0, qualityLevel}' ->'graphDisplayName' as dname
from data;
i was trying to recover two values with a single json selection, that is what puzzled me.