I have a jsonB field in postgresql DB table, it has data like this
{
"units": [
{
"id": 299872379221376,
"unitNumber": "1",
"unitFloorSpace": 1,
"createdTimeStamp": 1587994498586
},
{
"id": 299872417011074,
"unitNumber": "2",
"unitFloorSpace": 2,
"createdTimeStamp": 1588001330085
}
]
}
I just want to list all unitNumbers like below, what would be the query for that?
1,
2,
I have tried below json query but that doesn’t list
Select form_data -> units -> unitNumbers from table where row_id =1;
here is one way:
select jsonb_array_elements(jsonb_extract_path(jdata,'units')) ->> 'unitNumber' as UnitNumber
from tableName;
db<>fiddle here
Related
My Postgres DB Table BookingDetails has columns - id(bigint), info(jsonb)
My Json structure:
"bookingType": “special”,
“travellers”: [
{
"id": 1,
"nationality": "SomeValue",
}
],
“someTag”: “abc”
}
The travellers here is an array (and in this example, there’s only one element)
I want to:
Select records where nationality=‘CertainValue’
Update records set nationality=‘AnotherValue’ where nationality=‘CertainValue’
I could retrieve the array using:
select CAST (info->'travellers' AS TEXT) from BookingDetails
[
{
"id": 1,
"nationality": "SomeValue",
}
]
I could retrieve the array first element using:
select CAST (info->'travellers'->>0 AS TEXT) from BookingDetails
{
"id": 1,
"nationality": "SomeValue"
}
But how to do a select based on nationality=‘CertainValue’?
try this :
SELECT jsonb_set(info, array['travellers', (a.id - 1) :: text, 'nationality'], to_jsonb('AnotherValue' :: text))
FROM BookingDetails
CROSS JOIN LATERAL jsonb_array_elements(info->'travellers') WITH ORDINALITY AS a(content, id)
WHERE a.content->>'nationality' = 'CertainValue'
see the test result in dbfiddle
I have a jsonb column in my table and data is in this format:
[
{
"id": 1,
"DATA": {
"a": "XXX",
"key": "value1"
}
},
{
"id": 2,
"DATA": {
"a": "XXX",
"key": "value2"
}
}
]
I would like to get the count of rows in which key = value1. I tried some queries like:
select count(t.id)
from my_table t,
jsonb_array_elements(summary->'DATA') elem
where elem->>'key' = 'value1';
It returned 0 rows, though there are rows in db with that key value pair. Thanks in advance,
Use jsonb_array_elements() for the column summary as it is in the form of json array.
select count(distinct t.id)
from my_table t
cross join jsonb_array_elements(summary) elem
where elem->'DATA'->>'key' = 'value1';
Alternatively, you can get rid of the function using #> operator:
select count(t.id)
from my_table t
where summary #> '[{"DATA":{"key":"value1"}}]'
The second solution should be faster.
Db<>fiddle.
I have a JSON column with following JSON
{
"metadata": { "value": "JABC" },
"force": false,
"users": [
{ "id": "111", "comment": "abc" },
{ "id": "222", "comment": "abc" },
{ "id": "333" }
]
}
I am expecting list of IDs from the query output ["111","222", "333"]. I tried following query but getting null value.
select colName->'users'->>'id' ids from tableName
How to get this specific field value from the array of object?
You need to extract the array as rows and then get the id:
select json_array_elements(colName->'users')->>'id' ids from tableName;
If you're using jsonb rather than json, the function is jsonb_array_elements.
I'm using Presto and trying to extract all 'id' from 'source'='dd' from a nested json structure as following.
{
"results": [
{
"docs": [
{
"id": "apple1",
"source": "dd"
},
{
"id": "apple2",
"source": "aa"
},
{
"id": "apple3",
"source": "dd"
}
],
"group": 99806
}
]
}
expected to extract the ids [apple1, apple3] into a column in Presto
I am wondering what is the right way to achieve this in Presto Query?
If your data has a regular structure as in the example you posted, you can use a combination of parsing the value as JSON, casting it to a structured SQL type (array/map/row) and the using array processing functions to filter, transform and extract the elements you want:
WITH data(value) AS (VALUES '{
"results": [
{
"docs": [
{
"id": "apple1",
"source": "dd"
},
{
"id": "apple2",
"source": "aa"
},
{
"id": "apple3",
"source": "dd"
}
],
"group": 99806
}
]
}'),
parsed(value) AS (
SELECT cast(json_parse(value) AS row(results array(row(docs array(row(id varchar, source varchar)), "group" bigint))))
FROM data
)
SELECT
transform( -- extract the id from the resulting docs
filter( -- filter docs with source = 'dd'
flatten( -- flatten all docs arrays into a single doc array
transform(value.results, r -> r.docs) -- extract the docs arrays from the result array
),
doc -> doc.source = 'dd'),
doc -> doc.id)
FROM parsed
The query above produces:
_col0
------------------
[apple1, apple3]
(1 row)
I have a nested and hierarchical structure expressed in JSON e.g.:
{
"id":1,
"children": [
{ "id":2 },
{ "id": 3, "children": [
{ "id": 4 }
]
}
]
}
Can postgres answer a query whether the record contains "id": 4 in any part of the document?
If yes, are such queries backed by JSONB indexing added in version 9.4?
UPDATE: Thanks to therealgaxbo on reddit, we started with my original code and developed something more concise:
with recursive deconstruct (jsonlevel) as(
values ('{"id":1,"children":[{"id":2},{"id":3,"children":[{"id":4}]}]}'::json)
union all
select
case left(jsonlevel::text, 1)
when '{' then (json_each(jsonlevel)).value
when '[' then json_array_elements(jsonlevel)
end as jsonlevel
from
deconstruct
where
left(jsonlevel::text, 1) in ('{', '[')
)
select * from deconstruct where case when left(jsonlevel::text, 1) = '{' then jsonlevel->>'id' = '4' else false end;
My original response below:
I experimented like crazy and finally came up with something like this:
with recursive ret(jsondata) as
(select row_to_json(col)::text jsondata from
json_each('{
"id":1,
"children": [
{ "id":2 },
{ "id": 3, "children": [
{ "id": 4 }
]
}
]
}'::json) col
union
select case when left(jsondata::text,1)='[' then row_to_json(json_each(json_array_elements(jsondata)))::text
when left((jsondata->>'value'),2)='{}' then null::text
when left((jsondata->>'value')::text,1)='[' then row_to_json(json_each(json_array_elements(jsondata->'value')))::text
else ('{"key":'||(jsondata->'key')||', "value":'||(jsondata->'value')||'}')::json::text end jsondata
from (
select row_to_json(json_each(ret.jsondata::json)) jsondata
from ret) xyz
)
select max(1) from ret
where jsondata::json->>'key'='id'
and jsondata::json->>'value'='1'