My table looks like this:
id
data
1
{tags: {"env": "dev", "owner": "me"}}
I want to fetch the data and inside the select query convert the data column to the following format:
id
data
1
{tags: [{"key": "env", "value": "dev"}, {"key": "owner", "value": "me"}]}
I've tried several JSON mysql functions but the closest I got is :
id
data
1
{tags: [{"key": "env", "value": ["dev", "me"]}, {"key": "owner", "value": ["dev", "me"]}]}
Any suggestions?
Thanks
SELECT id, JSON_OBJECT("tags", JSON_ARRAY( JSON_OBJECT("key", "env", "value", JSON_EXTRACT(json_column, "$.tags.env")), JSON_OBJECT("key", "owner", "value", JSON_EXTRACT(json_column, "$.tags.owner")) )) as data FROM table_name
JSON_EXTRACT : extract the values of the "env" and "owner" keys from the json_column
JSON_OBJECT : create two JSON objects with the "key" and "value" keys and the extracted values
JSON_ARRAY : create a JSON array of these two objects
and finally wraps the array in another JSON_OBJECT with the "tags" key.
This is a generic approach which will also work on data fields that have multiple top-level keys and multiple second-level keys:
select t1.id, (select json_objectagg(t1.k1,
(select json_arrayagg(json_object('key', t2.k2,
'value', json_extract(t.data, concat('$.', t1.k1, '.', t2.k2))))
from json_table(json_keys(json_extract(t.data, concat('$.', t1.k1))), '$[*]' columns (k2 text path '$')) t2))
from json_table(json_keys(t.data), '$[*]' columns (k1 text path '$')) t1)
from tbl t;
Related
I'm trying to migrate Oracle 12c queries to Postgres11.5.
Here is the json:
{
"cost": [{
"spent": [{
"ID": "HR",
"spentamount": {
"amount": 2000.0,
"country": "US"
}
}]
}],
"time": [{
"spent": [{
"ID": "HR",
"spentamount": {
"amount": 308.91,
"country": "US"
}
}]
}]
}
Here is the query that has to be migrated to Postgres 11.5:
select js.*
from P_P_J r,
json_table(r.P_D_J, '$.*[*]'
COLUMNS(NESTED PATH '$.spent[*]'
COLUMNS(
ID VARCHAR2(100 CHAR) PATH '$.ID',
amount NUMBER(10,4) PATH '$.spentamount.amount',
country VARCHAR2(100 CHAR) PATH '$.spentamount.country'))
) js
The result:
ID, amount, country
HR, 2000.0,US
HR,308.91,US
I have two questions here:
What does $.*[*] mean?
How can we migrate this query in Postgres so that it directly looks at 'spent' instead of navigating 'cost'->'spent' or 'time'->'spent'
There is no direct replacement for json_table in Postgres. You will have to combine several calls to explode the JSON structure.
You didn't show us your expected output, but as far as I can tell, the following should do the same:
select e.item ->> 'ID' as id,
(e.item #>> '{spentamount, amount}')::numeric as amount,
e.item #>> '{spentamount, country}' as country
from p_p_j r
cross join jsonb_each(r.p_d_j) as a(key, val)
cross join lateral (
select *
from jsonb_array_elements(a.val)
where jsonb_typeof(a.val) = 'array'
) as s(element)
cross join jsonb_array_elements(s.element -> 'spent') as e(item)
;
The JSON path expression '$.*[*] means: iterate over all top-level keys, then iterate over all array elements found in there and the nested path '$.spent[*]' then again iterates over all array elements in there. These steps are reflected in the three JSON function calls that are needed to get there.
With Postgres 12, this would be a bit easier as this can be done with a single call to jsonb_path_query() which also use a JSON Path to access the elements using a very similar JSON path expression:
select e.item ->> 'ID' as id,
(e.item #>> '{spentamount, amount}')::numeric as amount,
e.item #>> '{spentamount, country}' as country
from p_p_j r
cross join jsonb_path_query(r.p_d_j, '$.*[*].spent[*]') as e(item)
;
Online example
I've got a JSON column containing an array of items:
[
{
"type": "banana"
},
{
"type": "apple"
},
{
"type": "orange"
}
]
I want to select one column with a concatenated type, resulting in 'banana, apple, orange'.
Thanks,
David
You need to parse and aggregate the stored JSON:
SELECT
JsonColumn,
NewColumn = (
SELECT STRING_AGG(JSON_VALUE([value], '$.type'), ',')
WITHIN GROUP (ORDER BY CONVERT(int, [key]))
FROM OPENJSON(t.JsonColumn)
)
FROM (VALUES
('[{"type":"banana"},{"type":"apple"},{"type":"orange"}]')
) t (JsonColumn)
Result:
JsonColumn
NewColumn
[{"type":"banana"},{"type":"apple"},{"type":"orange"}]
banana,apple,orange
I have a JSON like this (see the test setup below)
{
"dt" :
[
{
"values" :
[
{
"key" : "a"
},
{
"key" : "b"
}
]
}
]
}
and it is straightforeward to parse the inner array as it has keys as follows
SELECT tab.id,
jt.*
FROM parse_json_array tab,
json_table(data, '$.dt[*]'
COLUMNS (NESTED PATH '$.values[*]' COLUMNS(
key PATH '$.key' )
)) AS "JT"
where tab.id = 1;
which returns
ID, KEY
--------
1 a
1 b
But if the inner array has no keys, how could I addapt the path in NESTED PATH?
{
"dt" :
[
{
"values" :
[
"a",
"b"
]
}
]
}
All my try such as key PATH '$.*' or key PATH '*' return null or syntax error.
Note I do not need a solution, that parse both variants, but it would be of course a bonus;)
I'm on XE 18.4.0.0.0
Test data
create table parse_json_array
(id int primary key,
data CLOB constraint c1 check(data is JSON)
);
insert into parse_json_array (id, data) values (1, '{ "dt" : [ {"values" : [{"key" : "a"} , {"key" : "b" } ]} ] }');
insert into parse_json_array (id, data) values (2, '{ "dt" : [ {"values" : [ "a" , "b" ]}] }');
This will give you the id and the values within the nested array, when it's just an array of scalars rather than objects.
SELECT tab.id,
jt.*
FROM parse_json_array tab,
json_table(data, '$.dt[*].values[*]'
COLUMNS key PATH '$' )
AS "JT"
where tab.id = 2;
Storing JSON in both formats, and even more so, asking for a solution that works for both, doesn't make a lot of sense; the JSON structure is different. It's like asking for a SQL SELECT query that works for two different tables with different column sets.
If you need a solution with nested path (perhaps because you must pick out additional bits of data, which you did not share with us), you can do something like this (which is what Padders suggested in a comment):
SELECT tab.id,
jt.*
FROM parse_json_array tab,
json_table(data, '$.dt[*]' columns(
nested path '$.values[*]'
COLUMNS (key PATH '$' )) )
AS "JT"
where tab.id = 2;
EDIT:
To get values both from object members and from scalar members of the nested array, you can do something like this. Use nvl(k_token, token) if you just need the value and don't need to know if it comes from an array of objects or an array of scalars. Note that this solution will work even if you have objects and scalars mixed together in the same JSON (in the same nested array).
select p.id, j.k_token, j.token
from parse_json_array p,
json_table(data, '$.dt[*].values[*]'
columns( k_token path '$.key',
token path '$'
)
) j
;
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'm trying to migrate Oracle 12c queries to Postgres11.5.
Here is the json:
{
"cost": [{
"spent": [{
"ID": "HR",
"spentamount": {
"amount": 2000.0,
"country": "US"
}
}]
}],
"time": [{
"spent": [{
"ID": "HR",
"spentamount": {
"amount": 308.91,
"country": "US"
}
}]
}]
}
Here is the query that has to be migrated to Postgres 11.5:
select js.*
from P_P_J r,
json_table(r.P_D_J, '$.*[*]'
COLUMNS(NESTED PATH '$.spent[*]'
COLUMNS(
ID VARCHAR2(100 CHAR) PATH '$.ID',
amount NUMBER(10,4) PATH '$.spentamount.amount',
country VARCHAR2(100 CHAR) PATH '$.spentamount.country'))
) js
The result:
ID, amount, country
HR, 2000.0,US
HR,308.91,US
I have two questions here:
What does $.*[*] mean?
How can we migrate this query in Postgres so that it directly looks at 'spent' instead of navigating 'cost'->'spent' or 'time'->'spent'
There is no direct replacement for json_table in Postgres. You will have to combine several calls to explode the JSON structure.
You didn't show us your expected output, but as far as I can tell, the following should do the same:
select e.item ->> 'ID' as id,
(e.item #>> '{spentamount, amount}')::numeric as amount,
e.item #>> '{spentamount, country}' as country
from p_p_j r
cross join jsonb_each(r.p_d_j) as a(key, val)
cross join lateral (
select *
from jsonb_array_elements(a.val)
where jsonb_typeof(a.val) = 'array'
) as s(element)
cross join jsonb_array_elements(s.element -> 'spent') as e(item)
;
The JSON path expression '$.*[*] means: iterate over all top-level keys, then iterate over all array elements found in there and the nested path '$.spent[*]' then again iterates over all array elements in there. These steps are reflected in the three JSON function calls that are needed to get there.
With Postgres 12, this would be a bit easier as this can be done with a single call to jsonb_path_query() which also use a JSON Path to access the elements using a very similar JSON path expression:
select e.item ->> 'ID' as id,
(e.item #>> '{spentamount, amount}')::numeric as amount,
e.item #>> '{spentamount, country}' as country
from p_p_j r
cross join jsonb_path_query(r.p_d_j, '$.*[*].spent[*]') as e(item)
;
Online example