I have a json field in postgres db that contains data like
[{
"value": "+1 968 730 5680",
"label": "mobile",
"primary": true
},{
"value": "+1 909 169 4444",
"label": "mobile",
"primary": false
}]
I want to query this field to produce
+1 968 730 5680; +1 909 169 4444
Given that the number of elemets can vary.
I had enough brains to get the first element with
json_field -> 0 ->> 'value'
but am totally stuck at producing a string with all elements.
Please help.
UPDATE
Following advice below, I get an error with statement
select d ->> 'value' as val
from analyst.person
cross join jsonb_array_elements(phone) as x(d)
ERROR: column "phone" does not exist
LINE 3: cross join jsonb_array_elements(phone) as x(d)
another variant I tried
select d ->> 'value' as val
from analyst.person as person
cross join jsonb_array_elements(person.phone) as x(d)
gives error
ERROR: invalid reference to FROM-clause entry for table "person"
LINE 3: cross join jsonb_array_elements(person.phone) as x(d)
^
HINT: There is an entry for table "person", but it cannot be referenced from this part of the query.
You need to unnest your json array, extract the value and aggregate it back into a string:
select string_agg(val, '; ')
from (
select d ->> 'value' as val
from the_table
cross join lateral jsonb_array_elements(the_json_colum) as x(d)
) t
Online example: https://rextester.com/VFSRY99127
Related
I have a column named systemproperties and the data in it is in this format:
[
{"name": "system.totalphysicalmemory", "value": "4.00GB"},
{"name": "system.enablenetflow", "value": "false"}
]
This is the way how I get the value for totalphysicalmemory:
SELECT
jsonb_array_element(system_properties::jsonb, 0) ->> 'value' as total_physical_memory
FROM mytable
This one works but not all of the records have the same index for totalphysicalmemory. I am trying to find a way to get the value by name instead.
I tried to crashcourse on json/postgresql but I am not getting any good results. Thank you!
This is the way how I get the value for totalphysicalmemory:
SELECT
jsonb_array_element(system_properties::jsonb, 0) ->> 'value' as total_physical_memory
FROM mytable
You can use a JSON path query
select jsonb_path_query_first(systemproperties, '$[*] ?(#.name == "system.totalphysicalmemory").value)')
from mytable;
So here is my JSON column in my Postgres DB:
{
"objekt_art": {
"86": {
"code": "86",
"bezeichnung_de": "Kino",
"bezeichnung_fr": "Cinéma",
"bezeichnung_it": "Cinema",
"bezeichnung_en": null,
"kurz_bezeichnung_de": "Kino",
"relevant_fuer_berechnung_steuerquote": true
},
"27": {
"code": "27",
"bezeichnung_de": "Kiosk",
"bezeichnung_fr": "Kiosque",
"bezeichnung_it": "Chiosco",
"bezeichnung_en": null,
"kurz_bezeichnung_de": "Kiosk",
"relevant_fuer_berechnung_steuerquote": true
}
}
}
I need to be able to query the bezechnung_de for example where code = 86.
The number of code i can pass from another table.
How can i for example make a query with two columns. One with the number and the second with bezeichnung_de.
Like this:
Code Bez
86 Kino
Sample data structure and sample table for join data: dbfiddle
select
je.value -> 'code' as "Code",
je.value -> 'bezeichnung_de' as "Bez"
from
test t
cross join jsonb_each((data::jsonb ->> 'objekt_art')::jsonb) je
-- In table test_join I insert value 86 for join record
inner join test_join tj on je.key::int = tj.json_id
As you know the code, this is fairly easy:
select t.the_column -> 'objekt_art' -> '86' ->> 'code' as code,
t.the_column -> 'objekt_art' -> '86' ->> 'bezeichnung_de' as bez
from the_table t
where ...
The value '86' can be a parameter. The first expression to select the code isn't really needed though, as you could replace it with the constant value (=parameter) directly.
If the "outer" JSON key isn't the same value as the code value, you could use something like this:
select o.value ->> 'code' as code,
o.value ->> 'bezeichnung_de' as bez
from the_table t
cross join jsonb_each(t.the_column -> 'objekt_art') o(key, value)
where o.key = '86'
and ... other conditions ...
If you are using Postgres 13 or later, this can also be written as a JSON path expression:
select a.item ->> 'code' as code,
a.item ->> 'bezeichnung_de' as bez
from (
select jsonb_path_query_first(t.the_column, '$.objekt_art.* ? (#.code == "86")') as item
from the_table t
where ....
) a
All examples assume that the column is defined with the data jsonb which it should be. If it's not you need to cast it: the_column::jsonb
I am using JSON_MODIFY to build complex JSON. Moving from MySQL I am struggling with the JSON functions provided by SQL Server. The issue I'm having is that SQL Server seems to construct all JSON objects in an array. There is the WITHOUT_ARRAY_WRAPPER mechanism, which seems like it should do what I want, however; there are two undesirable consequences.
It only returns one result depending on how it is used
The result is a single string with escape characters
I have constructed a simple query which illustrates my needs and the issue.
QUERY 1
SELECT JSON_MODIFY(
JSON_QUERY('{"definitions": {"id": "INT", "name": "VARCHAR(23)"}}'),
'append $.data',
(
SELECT * FROM (
SELECT 1 AS id, '123abc' AS "name" UNION
SELECT 2 AS id, '234bcd' AS "name"
) AS "data"
FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
)
) AS "data";
OUTPUT 1
{
"definitions":{
"id":"INT",
"name":"VARCHAR(23)"
},
"data":[
"{\"id\":1,\"name\":\"123abc\"},{\"id\":2,\"name\":\"234bcd\"}"
]
}
QUERY 2
SELECT JSON_MODIFY(
JSON_QUERY('{"definitions": {"id": "INT", "name": "VARCHAR(23)"}}'),
'append $.data',
(
SELECT * FROM (
SELECT 1 AS id, '123abc' AS "name" UNION
SELECT 2 AS id, '234bcd' AS "name"
) AS "data"
FOR JSON PATH
)
) AS "data";
OUTPUT 2
{
"definitions":{
"id":"INT",
"name":"VARCHAR(23)"
},
"data":[
[
{"id":1, "name":"123abc"},
{"id":2, "name":"234bcd"}
]
]
}
QUERY 1
The data object is an array (which is expected), but the problem is what is in the array... A single string with escape characters.
QUERY 2
The data object is an array, which contains an array. In order to access the actual array of data, I would use something like for each obj in data[0].... The problem this poses is, for anyone consuming the JSON object, I would have to tell them:
"In this particular object the data element is an array of
arrays--You'll want to use the first and only the first
element to access the actual array of data."
I've naively tried many different combinations of JSON_MODIFY, JSON_QUERY, and CONCAT to no avail. How can I properly use JSON_MODIFY to get the following output, without the double array in data?
{
"definitions":{
"id":"INT",
"name":"VARCHAR(23)"
},
"data":[
{"id":1, "name":"123abc"},
{"id":2, "name":"234bcd"}
]
}
You are over-thinking this by trying to JSON_MODIFY an existing object.
Construct the definitions and data properties that you need, inside a subquery if necessary.
Then use FOR JSON a second time to get the outer object.
SELECT
definitions = JSON_QUERY('{"id": "INT", "name": "VARCHAR(23)"}'),
data =
(
SELECT id, name
FROM (VALUES
(1, '123abc'),
(2, '234bcd')
) v(id, name)
FOR JSON PATH
)
FOR JSON PATH;
SQL Fiddle
By trial and error, I found the solution.
Removed the append keyword from the path parameter in the JSON_MODIFY statement
Removed the WITHOUT_ARRAY_WRAPPER parameter from the FOR JSON statement.
Now the results are as expected and I don't need to explain to any consumers to "Just use data[0]"
The Query
SELECT JSON_MODIFY(
JSON_QUERY('{"definitions": {"id": "INT", "name": "VARCHAR(23)"}}'),
'$.data',
(
SELECT * FROM (
SELECT 1 AS id, '123abc' AS "name" UNION
SELECT 2 AS id, '234bcd' AS "name"
) AS "data"
FOR JSON PATH
)
) AS "data";
Produces the following output
{
"definitions":{
"id":"INT",
"name":"VARCHAR(23)"
},
"data":[
{"id":1, "name":"123abc"},
{"id":2, "name":"234bcd"}
]
}
I have a table with JSON field which contains an array of JSON objects. I need to select objects by some condition.
Create and fill a table:
CREATE TABLE test (
id INT AUTO_INCREMENT PRIMARY KEY,
json_list JSON
);
INSERT INTO test(json_list) VALUES
("{""list"": [{""type"": ""color"", ""value"": ""red""}, {""type"": ""shape"", ""value"": ""oval""}, {""type"": ""color"", ""value"": ""green""}]}"),
("{""list"": [{""type"": ""shape"", ""value"": ""rect""}, {""type"": ""color"", ""value"": ""olive""}]}"),
("{""list"": [{""type"": ""color"", ""value"": ""red""}]}")
;
Now I need to select all objects with type = color from all rows.
I want to see this output:
id extracted_value
1 {"type": "color", "value": "red"}
1 {"type": "color", "value": "green"}
2 {"type": "color", "value": "olive"}
3 {"type": "color", "value": "red"}
It would be good to get this too:
id color
1 red
1 green
2 olive
3 red
I can't change the DB or JSON.
I'm using MySQL 5.7
My current solution
My solution is to cross join the table with some index set and then extract all elements of JSON array.
I don't like it as if possible object count in one array is large it is required to have all indexes till the maximum one. It makes the query slow as it won't stop calculation of JSON value when the end of array is reached.
SELECT
test.id,
JSON_EXTRACT(test.json_list, CONCAT('$.list[', ind.ind, ']')),
ind.ind
FROM
test
CROSS JOIN
(SELECT 0 AS ind UNION ALL SELECT 1 AS ind UNION ALL SELECT 2 AS ind) ind
WHERE
JSON_LENGTH(json_list, "$.list") > ind.ind
AND JSON_EXTRACT(json_list, CONCAT('$.list[', ind.ind, '].type')) = "color";
It is easy to get only values by changing JSON_EXTRACT path. But is it there a better way?
Edits
Added a check for json_list.list length. This filtered out 67% of derived table rows in this case.
SELECT JSON_EXTRACT(json_list, '$.list[*]')
FROM `test`
where JSON_CONTAINS(json_list, '{"type":"color"}', '$.list')
So current best solution is mine:
SELECT
test.id,
JSON_EXTRACT(test.json_list, CONCAT('$.list[', ind.ind, ']')),
ind.ind
FROM
test
CROSS JOIN
(SELECT 0 AS ind UNION ALL SELECT 1 AS ind UNION ALL SELECT 2 AS ind) ind
WHERE
JSON_LENGTH(json_list, "$.list") > ind.ind
AND JSON_EXTRACT(json_list, CONCAT('$.list[', ind.ind, '].type')) = "color";
Hi I have a colum jsnoḃ with this values
proyectos:
nomḃre:character_varying
fecha:datetime
campos: jsonḃ
the value of campos is =
{"lista": [{"valor": "10", "nombre": "sueldo"}, {"valor": "20", "nombre": "sueldo"}, {"valor": "25", "nombre": "sueldo"}]}
I I run this query ḃut not working
SELECT jsonb_array_elements(campos->'lista')->'nombre' as content,
sum(((jsonb_array_elements(campos->'lista')->'valor'))::numeric) as cantidad
FROM proyectos GROUP BY jsonb_array_elements(campos->'lista')->'nombre
The console show me the message:
ERROR: cannot cast type jsonb to numeric
LINE 3: ...((jsonb_array_elements(campos->'lista')->'valor'))::numeric)...
^
********** Error **********
ERROR: cannot cast type jsonb to numeric
SQL state: 42846
Character: 137
Any idea ?
Use the function jsonb_array_elements() in a lateral join to get array elements as value, the ->> operator to get json objects as text and cast the valor objects to numeric.
select value->>'nombre' as nombre, sum((value->>'valor')::numeric)
from proyectos
cross join jsonb_array_elements(campos->'lista')
group by 1
nombre | sum
--------+-----
sueldo | 55
(1 row)