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Is there a way to replace the JSON value and set it to '' at the same time?
(2 answers)
Closed last month.
I have JSON fields the looks like this
Columns
[{"header":"C", "value": 1},{"header":"D", "value": 2},{"header":"E", "value": 3}]
[{"test":"C", "value": 1},{"test":"D", "value": 2},{"test":"E", "value": 3}]
I want to change the name of the JSON value header and set it to '', but I was only able to change the value.
UPDATE Files SET Columns = REPLACE(Columns, '"header":', '"test":')
I want it to look like this:
Columns
[{"test":"", "value": 1},{"test":"", "value": 2},{"test":"", "value": 3}]
[{"test":"C", "value": 1},{"test":"D", "value": 2},{"test":"E", "value": 3}]
I have the script to change the header key to be test but it is clearing the existing JSON key for test that have values in them.
How do I keep the 2nd value the same while also clearing the first value and changing the name of it? Do I need to add a WHERE header exists?
UPDATE Files
SET Columns = (
SELECT test = '', value
FROM OPENJSON(Columns)
WITH (
header varchar(50),
value varchar(50)
) j
FOR JSON PATH
);
You may try to modify your second statement and include an additional test column in the explicit schema:
UPDATE Files
SET Columns = (
SELECT COALESCE(test, '') AS test, value
FROM OPENJSON (Columns) WITH (
test varchar(50) 'lax $.test',
value int 'lax $.value'
)
FOR JSON PATH
)
Related
I am trying to convert JSON array data into tabular format using Json_Table function. I tried to run the below query but I am getting the following errors:
SQL/JSON scalar required.. SQLCODE=-16413, SQLSTATE=2203F, DRIVER=4.19.56).
The same query is working fine when the number of elements in Employees array is 1, but not otherwise.
SELECT E."id", E."name"
FROM JSON_TABLE
(
'{
"Employees": [
{
"id": 1,
"name": "Kathi"
},
{
"id": 2,
"name": "Pavan"
}
]
}', 'strict $' COLUMNS
(
"id" INTEGER PATH 'strict $.Employees[*].id'
, "name" VARCHAR(20) PATH 'strict $.Employees[*].name'
) ERROR ON ERROR
) AS E;
Just for the benefit of others who are looking for some examples, i found below link in internet, example 3 basically helps with my case. We need to use JSON_Table from SysTools schema.
https://www.worldofdb2.com/profiles/blogs/convert-json-data-to-relational-format
JSON_TABLE produces 1 row only per 1 json document.
You may use the following only:
"id" INTEGER PATH 'strict $.Employees[n].id'
, "name" VARCHAR(20) PATH 'strict $.Employees[n].name'
where n={0, 1} for an array of 2 elements as in your example.
I have the below sample JSON:
{
"Id1": {
"name": "Item1.jpg",
"Status": "Approved"
},
"Id2": {
"name": "Item2.jpg",
"Status": "Approved"
}
}
and I am trying to get the following output:
_key name Status
Id1 Item1.jpg Approved
Id2 Item2.jpg Approved
Is there any way I can achieve this in Snowflake using SQL?
You should use Snowflake's VARIANT data type in any column holding JSON data. Let's break this down step by step:
create temporary table FOO(v variant); -- Temp table to hold the JSON. Often you'll see a variant column simply called "V"
-- Insert into the variant column. Parse the JSON because variants don't hold string types. They hold semi-structured types.
insert into FOO select parse_json('{"Id1": {"name": "Item1.jpg", "Status": "Approved"}, "Id2": {"name": "Item2.jpg", "Status": "Approved"}}');
-- See how it looks in its raw state
select * from FOO;
-- Flatten the top-level JSON. The flatten function breaks down the JSON into several usable columns
select * from foo, lateral flatten(input => (foo.v)) ;
-- Now traverse the JSON using the column name and : to get to the property you want. Cast to string using ::string.
-- If you must have exact case on your column names, you need to double quote them.
select KEY as "_key",
VALUE:name::string as "name",
VALUE:Status::string as "Status"
from FOO, lateral flatten(input => (FOO.V)) ;
I have a local table variable that I'm trying to populate with JSON key-value pairs. Sometimes the values are themselves JSON strings
DECLARE #Values TABLE
(
JsonKey varchar(200),
JsonValue varchar(max)
)
An example of what this ends up looking like:
+---------+--------------------------------------+
| JsonKey | JsonValue |
+---------+--------------------------------------+
| foo | bar |
| foo | [{"label":"fooBar","Id":"fooBarId"}] |
+---------+--------------------------------------+
After populating it, I attempt to build it all up into a single JSON string, like so:
DECLARE #Json JSON =
(
SELECT V.JsonKey as 'name',
V.JsonValue as 'value'
FROM #Values V
for json path
)
The problem with this is that it turns the JSON values into a string, rather than treating them as JSON. This results in those values not being parsed correctly.
An example of what it ends up looking like:
[
{
"name": "foo",
"value": "bar"
},
{
"name": "foo",
"value": "[{\"label\":\"fooBar\",\"Id\":\"fooBarId\"}]"
}
]
I am trying to get the JSON for the second value to NOT be escaped or wrapped in double quotes. What I would like to see is this:
[
{
"name": "foo",
"value": "bar"
},
{
"key": "foo",
"value": [
{
"label": "fooBar",
"Id": "fooBarId"
}
]
}
]
If that value will ONLY ever be JSON, I can instead use JSON_QUERY() in the JSON build-up, like this:
DECLARE #Json JSON =
(
SELECT V.JsonKey as 'name',
JSON_QUERY(V.JsonValue) as 'value'
FROM #Values V
for json path
)
Building it up like this gives me the result I want, but errors when the JsonValue column is not valid JSON. I attempted to put it in a case statement, to only use JSON_QUERY() when JsonValue was valid JSON, but since case statements are required to always output the same type, it turned it into a string again, and I got a repeat of the first example. I have not been able to find an elegant solution to this, and it really feels like there should be one that I'm just missing. Any help will be appreciated
One possible approach is to generate a statement with duplicate column names (JsonValue). By default FOR JSON AUTO does not include NULL values in the output, so the result is the expected JSON. Just note, that you must not use INCLUDE_NULL_VALUES in the statement or the final JSON will contain duplicate keys.
Table:
DECLARE #Values TABLE (
JsonKey varchar(200),
JsonValue varchar(max)
)
INSERT INTO #Values
(JsonKey, JsonValue)
VALUES
('foo', 'bar'),
('foo', '[{"label":"fooBar","Id":"fooBarId"}]')
Statement:
SELECT
JsonKey AS [name],
JSON_QUERY(CASE WHEN ISJSON(JsonValue) = 1 THEN JSON_QUERY(JsonValue) END) AS [value],
CASE WHEN ISJSON(JsonValue) = 0 THEN JsonValue END AS [value]
FROM #Values
FOR JSON AUTO
Result:
[{"name":"foo","value":"bar"},{"name":"foo","value":[{"label":"fooBar","Id":"fooBarId"}]}]
I have a table say types, which had a JSON column, say location that looks like this:
{ "attribute":[
{
"type": "state",
"value": "CA"
},
{
"type": "distance",
"value": "200.00"
} ...
]
}
Each row in the table has the data, and all have the "type": "state" in it. I want to just extract the value of "type": "state" from every row in the table, and put it in a new column. I checked out several questions on SO, like:
Query for element of array in JSON column
Index for finding an element in a JSON array
Query for array elements inside JSON type
but could not get it working. I do not need to query on this. I need the value of this column. I apologize in advance if I missed something.
create table t(data json);
insert into t values('{"attribute":[{"type": "state","value": "CA"},{"type": "distance","value": "200.00"}]}'::json);
select elem->>'value' as state
from t, json_array_elements(t.data->'attribute') elem
where elem->>'type' = 'state';
| state |
| :---- |
| CA |
dbfiddle here
I mainly use Redshift where there is a built-in function to do this. So on the off-chance you're there, check it out.
redshift docs
It looks like Postgres has a similar function set:
https://www.postgresql.org/docs/current/static/functions-json.html
I think you'll need to chain three functions together to make this work.
SELECT
your_field::json->'attribute'->0->'value'
FROM
your_table
What I'm trying is a json extract by key name, followed by a json array extract by index (always the 1st, if your example is consistent with the full data), followed finally by another extract by key name.
Edit: got it working for your example
SELECT
'{ "attribute":[
{
"type": "state",
"value": "CA"
},
{
"type": "distance",
"value": "200.00"
}
]
}'::json->'attribute'->0->'value'
Returns "CA"
2nd edit: nested querying
#McNets is the right, better answer. But in this dive, I discovered you can nest queries in Postgres! How frickin' cool!
I stored the json as a text field in a dummy table and successfully ran this:
SELECT
(SELECT value FROM json_to_recordset(
my_column::json->'attribute') as x(type text, value text)
WHERE
type = 'state'
)
FROM dummy_table
I'm new to the postgreSQL(9.5) Json world. Looking for help writing this query. Take this simplified table as an example.
CREATE TABLE activity_log (uri varchar,
data jsonb );
Example of data inside of 'data' column.
"{"ListingInputFilterBean":{"searchItems": [], "listingStatus": "ACTIVE"}"
"{"ListingInputFilterBean":{"searchItems": [{"name": "Dachshund", "type": "BREED"}], "listingStatus": "ACTIVE"}}"
"{"ListingInputFilterBean":{"searchItems": [{"name": "Lab", "type": "BREED"}, {"name": "Black Lab", "type": "CST"}], "listingStatus": "ACTIVE"}}"
The 'data' column is used to log specific sets of data for each URI call. In this case the searchItems array contain the items used in the search. I'm looking to write a query that finds the most searched for 'breed'. I'd like to count the number of times each 'name' is used when type is 'BREED'.
My initial approach was to pull back each of the 'searchItems'. Turn those into a row set using jsonb_to_recordset, but I quickly got in over my head when reading the documentation (sorry, I'm a noob).
Any suggestions on how to write that SQL?
WITH log_activity(data) AS ( VALUES
('{"ListingInputFilterBean":{"searchItems": [], "listingStatus": "ACTIVE"}}'::JSONB),
('{"ListingInputFilterBean":{"searchItems": [{"name": "Dachshund", "type": "BREED"}], "listingStatus": "ACTIVE"}}'::JSONB),
('{"ListingInputFilterBean":{"searchItems": [{"name": "Lab", "type": "BREED"}, {"name": "Black Lab", "type": "CST"}], "listingStatus": "ACTIVE"}}'::JSONB)
)
SELECT search_item->>'name',count(search_item->>'name')
FROM
log_activity la,
jsonb_array_elements(la.data#>'{ListingInputFilterBean,searchItems}') as search_item
WHERE search_item->>'type' = 'BREED'
GROUP BY search_item;
Result:
name | count
-----------+-------
Lab | 1
Dachshund | 1
(2 rows)
Here you just need to iterate over the list of searchItems and group only those entries, which do match your criteria. Steps are the following:
Get jsonb array of searchItems with #> operator, it will get JSON object at specified path;
Iterate over the list of elements retrieved from step 1 with jsonb_array_elements(), function which expands a JSON array to a set of JSON values;
count() names where searchItems' type = BREED, you can get actual text value with ->> operator;
UPDATE
With jsonb_to_recordset() it looks shorter, but you need explicitly define search_item columns' types:
SELECT search_item.name ,count(search_item.name)
FROM
log_activity la,
jsonb_to_recordset(la.data#>'{ListingInputFilterBean,searchItems}') as search_item(name text,type text)
WHERE search_item.type = 'BREED'
GROUP BY search_item.name;