How do I access the value of a object property, inside an array, using JSON_QUERY in MariaDB? I have a JSON field with following data, and want to access the value of the section property.
[
[
{"section": "search"}
]
]
The following SQL is returning NULL
SELECT JSON_QUERY('[[{"section": "search"}]]', '$[0][0].section') FROM mytable
For anyone else having the same issue, you have to use JSON_VALUE for accessing scalar values. The following query gives the expected result.
SELECT JSON_VALUE'[[{"section": "search"}]]', '$[0][0].section') FROM mytable;
JSON_QUERY vs JSON_VALUE
Related
This is driving me nuts, and I don't understand what's wrong with my approach.
I generate a JSON object in SQL like this:
select #output = (
select distinct lngEmpNo, txtFullName
from tblSecret
for json path, root('result'), include_null_values
)
I get a result like this:
{"result":[{"lngEmpNo":696969,"txtFullName":"Clinton, Bill"}]}
ISJSON() confirms that it's valid JSON, and JSON_QUERY(#OUTPUT, '$.result') will return the array [] portion of the JSON object... cool!
BUT, I'm trying to use JSON_QUERY to extract a specific value:
This gets me a NULL value. Why??????? I've tried it with the [0], without the [0], and of course, txtFullName[0]
SELECT JSON_QUERY(#jsonResponse, '$.result[0].txtFullName');
I prefixed with strict, SELECT JSON_QUERY(#jsonResponse, 'strict $.result[0].txtFullName');, and it tells me this:
Msg 13607, Level 16, State 4, Line 29
JSON path is not properly formatted. Unexpected character 't' is found at
position 18.
What am I doing wrong? What is wrong with my structure?
JSON_QUERY will only extract an object or an array. You are trying to extract a single value so, you need to use JSON_VALUE. For example:
SELECT JSON_VALUE(#jsonResponse, '$.result[0].txtFullName');
I have a big JSON data in one column called response_return in a Postgres DB, with a response like:
{
"customer_payment":{
"OrderId":"123456789",
"Customer":{
"Full_name":"Francis"
},
"Payment":{
"AuthorizationCode":"9874565",
"Recurrent":false,
"Authenticate":false,
...
}
}
}
I tried to use Postgres functions like -> ,->> ,#> or #> to walk through headers to achieve AuthorizationCode for a query.
When I use -> in customer_payment in a SELECT, returns all after them. If I try with OrderId, it's returned NULL.
The alternatives and sources:
Using The JSON Datatype In PostgreSQL
Operator ->
Allows you to select an element based on its name.
Allows you to select an element within an array based on its index.
Can be used sequentially: ::json->'elementL'->'subelementM'->…->'subsubsubelementN'.
Return type is json and the result cannot be used with functions and operators that require a string-based datatype. But the result can be used with operators and functions that require a json datatype.
Query for element of array in JSON column
This is not helpful because I don't want filter and do not believe that need to transform to array.
If you just want to get a single attribute, you can use:
select response_return -> 'customer_payment' -> 'Payment' ->> 'AuthorizationCode'
from the_table;
You need to use -> for the intermediate access to the keys (to keep the JSON type) and ->> for the last key to return the value as a string.
Alternatively you can provide the path to the element as an array and use #>>
select response_return #>> array['customer_payment', 'Payment', 'AuthorizationCode']
from the_table;
Online example
I have the following data in a json column:
[
["model-1", 0.06232],
["model-2", 0.33587],
["model-3", 0.04962],
["model-4", 0.235],
["model-5", 0.31719]
]
My goal is to prepend a string to the first element of each inner list so that the output becomes:
[
["somestr/model-1", 0.06232],
["somestr/model-2", 0.33587],
["somestr/model-3", 0.04962],
["somestr/model-4", 0.235],
["somestr/model-5", 0.31719]
]
I have been able to "extract" the first elements using mariadb JSON_EXTRACT as follows:
SELECT JSON_EXTRACT(factors, '$[*][0]') FROM my_table;
But could not get any further.
Is it possible to achieve this using mariadb / mysql JSON functions? Or am I better off doing this on the application level?
I'm trying to write a SQL statement that will parse some JSON and return only rows where one of the arrays in the JSON Object contains a given value.
Example JSON:
Object 1:
{
"Key1": ["item1", "item2", "item3"]
}
Object 2:
{
"Key1": ["item1", "item3"]
}
I would like to only return rows where JSON_QUERY(object, '$.Key1').Contains("item2") is true (in this example, Object 1).
Of course, this magical function 'Contains()' does not exist in tsql, and I can't find any documentation of a function that performs as I'd like.
EDIT:
My current solution (which I'm not very fond of and would like to replace) checks if the string literal '"item1"' is contained within the value returned by JSON_QUERY. I don't like this, because it's possible an entry in the array could have a value like '123123"item1"123123', and then the conditional would return true.
Christian,
Sounds to me like your SQL Query could use a where clause using a LIKE comparison on a column
WHERE col1 LIKE 'some%funky%string'
The % is a wildcard declaritive
You can use OPENJSON to get a derived result set out of a json list or array:
The followin query uses JSON_QUERY to retrieve the list of strings within Key1. This is passed as argument into OPENJSON to retrive the list of strings as derived table:
DECLARE #jsonTable TABLE(ID INT IDENTITY, JsonString NVARCHAR(MAX));
INSERT INTO #jsonTable VALUES
(N'{
"Key1": ["item1", "item2", "item3"]
}')
,(N'{
"Key1": ["item1", "item3"]
}');
DECLARE #LookFor NVARCHAR(100)='Item2'
SELECT jt.ID
,jt.JsonString
,A.value
FROM #jsonTable jt
OUTER APPLY OPENJSON(JSON_QUERY(jt.JsonString,N'$.Key1')) AS A
--WHERE A.value=#LookFor
Uncomment the final WHERE to reduce the list to the rows with a value of Item2 (as defined in the variable #LookFor).
I have an SQL Table which one of the columns contain a JSON array in the following format:
[
{
"id":"1",
"translation":"something here",
"value":"value of something here"
},
{
"id":"2",
"translation":"something else here",
"value":"value of something else here"
},
..
..
..
]
Is there any way to use an SQL Query and retrieve columns with the ID as header and the "value" as the value of the column? Instead of return only one column with the JSON array.
For example, if I run:
SELECT column_with_json FROM myTable
It will return the above array. Where I want to return
1,2
value of something here, value of something else here
You can't use SQL to retrieve columns from the JSON stored inside the table: to the database engine the JSON is just unstructured text saved in a text field.
Some relational databases, like PostgreSQL, have a JSON type and functions to support JSON query. If this is your case, you should be able to perform the query you want.
Check this for an example on how it work with PostgreSQL:
http://clarkdave.net/2013/06/what-can-you-do-with-postgresql-and-json/