I want to remove the array wrapper surrounding a query result as I'm running a for loop to push the object into an array. This is my query
"SELECT * FROM jobs WHERE id = ? FOR JSON PATH, WITHOUT_ARRAY_WRAPPER"
but I'm getting this result in postman
{
"status": "Failed",
"message": "You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'JSON PATH, WITHOUT_ARRAY_WRAPPER' at line 1"
}
for json path is a feature of Microsoft SQL Server. There is a standard for JSON in SQL, but don't expect most SQL servers to follow it.
You can get a single JSON object for each row with json_object.
-- {"id": 2, "name": "Bar"}
select
json_object('id', id, 'name', name)
from jobs
where id = 2
Rather than query each job individually and then appending to an array, you can do this in single query using the in operator to query all desired rows at once, and then json_arrayagg to aggregate them into a single array.
-- [{"id": 1, "name": "Foo"},{"id": 3, "name": "Baz"}]
select
json_arrayagg( json_object('id', id, 'name', name) )
from jobs
where id in (1, 3)
This is much more efficient. In general, if you're querying SQL in loops there's a better way.
Demonstration.
Related
{
"TaskType": "kkkk",
"Status": "SUCCESS",
"jobID": "18056",
"DownloadFilePath": "https://abcd",
"accountId": "1234",
"customerId": "hhff"
}
This is sample data in message in notification table. I need to search for the keyword inside 3 or 4 fields out of 6 fields.
One way is to use multiple OR statements like:
SELECT message AS note
FROM notification
WHERE message::jsonb->'TaskType' LIKE '%1234%'
OR message::jsonb->'jobId' LIKE '%1234%'
OR message::jsonb->'Status' LIKE '%1234%';
The results are satisfactory, but is there a way to optimize the query in case I need to search in more fields.
you could just cast the message column to text and search inside the text:
SELECT message AS note
FROM notification
WHERE message::text like '%1234%'
You need to iterate through all key/value pairs:
select n.*
from notification n
where exists (select *
from jsonb_each_text(n.message) as m(key,value)
where key in ('TaskType', 'jobId', 'Status')
and value like '%1234%');
If you want to search in all values, just leave out the key in (..) part in the sub-select.
Searching in all values can be done using a JSON path operator in Postgres 12 or later:
select *
from notification
where message ## '$.* like_regex "1234"'
This assumes that messages is defined as jsonb - which it should be. If it's not, you need to cast it: message::jsonb
I have a column of JSON type in a postgres table. It currently has values like this
{"value": "abc"}
I want to write a SQL query that can change this to
[{"value": "abc", "timestamp": 1465373673}]
The part timestamp: 1465373673 will be hard coded
Any ideas on how this SQL query can be written?
You can use json_build_array and json_build_object:
UPDATE test
set a = json_build_array(
json_build_object('value', a->'value', 'timestamp', 1465373673)
);
Here's a fiddle.
Use the concatenation operator and the function jsonb_build_array():
select jsonb_build_array('{"value": "abc"}'::jsonb || '{"timestamp": 1465373673}');
jsonb_build_array
---------------------------------------------
[{"value": "abc", "timestamp": 1465373673}]
(1 row)
Read JSON Functions and Operators.
I have searched extensively (in Postgres docs and on Google and SO) to find examples of JSON functions being used on actual JSON columns in a table.
Here's my problem: I am trying to extract key values from an array of JSON objects in a column, using jsonb_to_recordset(), but get syntax errors. When I pass the object literally to the function, it works fine:
Passing JSON literally:
select *
from jsonb_to_recordset('[
{ "id": 0, "name": "400MB-PDF.pdf", "extension": ".pdf",
"transferId": "ap31fcoqcajjuqml6rng"},
{ "id": 0, "name": "1000MB-PDF.pdf", "extension": ".pdf",
"transferId": "ap31fcoqcajjuqml6rng"}
]') as f(name text);`
results in:
400MB-PDF.pdf
1000MB-PDF.pdf
It extracts the value of the key "name".
Here's the JSON in the column, being extracted using:
select journal.data::jsonb#>>'{context,data,files}'
from journal
where id = 'ap32bbofopvo7pjgo07g';
resulting in:
[ { "id": 0, "name": "400MB-PDF.pdf", "extension": ".pdf",
"transferId": "ap31fcoqcajjuqml6rng"},
{ "id": 0, "name": "1000MB-PDF.pdf", "extension": ".pdf",
"transferId": "ap31fcoqcajjuqml6rng"}
]
But when I try to pass jsonb#>>'{context,data,files}' to jsonb_to_recordset() like this:
select id,
journal.data::jsonb#>>::jsonb_to_recordset('{context,data,files}') as f(name text)
from journal
where id = 'ap32bbofopvo7pjgo07g';
I get a syntax error. I have tried different ways but each time it complains about a syntax error:
Version:
PostgreSQL 9.4.10 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2, 64-bit
The expressions after select must evaluate to a single value. Since jsonb_to_recordset returns a set of rows and columns, you can't use it there.
The solution is a cross join lateral, which allows you to expand one row into multiple rows using a function. That gives you single rows that select can act on. For example:
select *
from journal j
cross join lateral
jsonb_to_recordset(j.data#>'{context, data, files}') as d(id int, name text)
where j.id = 'ap32bbofopvo7pjgo07g'
Note that the #>> operator returns type text, and the #> operator returns type jsonb. As jsonb_to_recordset expects jsonb as its first parameter I'm using #>.
See it working at rextester.com
jsonb_to_recordset is a set-valued function and can only be invoked in specific places. The FROM clause is one such place, which is why your first example works, but the SELECT clause is not.
In order to turn your JSON array into a "table" that you can query, you need to use a lateral join. The effect is rather like a foreach loop on the source recordset, and that's where you apply the jsonb_to_recordset function. Here's a sample dataset:
create table jstuff (id int, val jsonb);
insert into jstuff
values
(1, '[{"outer": {"inner": "a"}}, {"outer": {"inner": "b"}}]'),
(2, '[{"outer": {"inner": "c"}}]');
A simple lateral join query:
select id, r.*
from jstuff
join lateral jsonb_to_recordset(val) as r("outer" jsonb) on true;
id | outer
----+----------------
1 | {"inner": "a"}
1 | {"inner": "b"}
2 | {"inner": "c"}
(3 rows)
That's the hard part. Note that you have to define what your new recordset looks like in the AS clause -- since each element in our val array is a JSON object with a single field named "outer", that's what we give it. If your array elements contain multiple fields you're interested in, you declare those in a similar manner. Be aware also that your JSON schema needs to be consistent: if an array element doesn't contain a key named "outer", the resulting value will be null.
From here, you just need to pull the specific value you need out of each JSON object using the traversal operator as you were. If I wanted only the "inner" value from the sample dataset, I would specify select id, r.outer->>'inner'. Since it's already JSONB, it doesn't require casting.
I have an issue where I have some JSON stored in my oracle database, and I need to extract values from it.
The problem is, there are some fields that are duplicated.
When I try this, it works as there is only one firstname key in the options array:
SELECT
JSON_VALUE('{"increment_id":"2500000043","item_id":"845768","options":[{"firstname":"Kevin"},{"lastname":"Test"}]}', '$.options.firstname') AS value
FROM DUAL;
Which returns 'Kevin'.
However, when there are two values for the firstname field:
SELECT JSON_VALUE('{"increment_id":"2500000043","item_id":"845768","options":[{"firstname":"Kevin"},{"firstname":"Okay"},{"lastname":"Test"}]}', '$.options.firstname') AS value
FROM DUAL;
It only returns NULL.
Is there any way to select the first occurence of 'firstname' in this context?
JSON_VALUE returns one SQL VALUE from the JSON data (or SQL NULL if the key does not exists).
If you have a collection of values (a JSON array) an you want one specific item of the array you use array subscripts (square brackets) like in JavaScript, for example [2] to select the third item. [0] selects the first item.
To get the first array item in your example you have to change the path expression from '$.options.firstname' to '$.options[0].firstname'
You can follow this query:-
SELECT JSON_VALUE('{
"increment_id": "2500000043",
"item_id": "845768",
"options": [
{
"firstname": "Kevin"
},
{
"firstname": "Okay"
},
{
"lastname": "Test"
}
]
}', '$.options[0].firstname') AS value
FROM DUAL;
I have a column which saves json values as text. I want to select columns in query based on a certain value contained in the text field.
To be clear, I have a column server_response which saves data as follows:
{
"Success": true,
"PasswordNotExpired": true,
"Exists": true,
"Status": "A",
"Err": null,
"Statuscode": 200,
"Message": "Login Denied"
}
How can i choose columns based on if the message was/or contained Login Denied in the where clause?
This should do the trick, at least this is what i understood you want:
SELECT * FROM table WHERE server_response LIKE '%Login Denied%'
I think you need a query like this:
SELECT *
FROM yourTable
WHERE server_response->>Message LIKE '%Login Denied%'
Note: source
The -> operator returns a JSON object.
The ->> operator returns TEXT.