I have an SQL Table which one of the columns contain a JSON array in the following format:
[
{
"id":"1",
"translation":"something here",
"value":"value of something here"
},
{
"id":"2",
"translation":"something else here",
"value":"value of something else here"
},
..
..
..
]
Is there any way to use an SQL Query and retrieve columns with the ID as header and the "value" as the value of the column? Instead of return only one column with the JSON array.
For example, if I run:
SELECT column_with_json FROM myTable
It will return the above array. Where I want to return
1,2
value of something here, value of something else here
You can't use SQL to retrieve columns from the JSON stored inside the table: to the database engine the JSON is just unstructured text saved in a text field.
Some relational databases, like PostgreSQL, have a JSON type and functions to support JSON query. If this is your case, you should be able to perform the query you want.
Check this for an example on how it work with PostgreSQL:
http://clarkdave.net/2013/06/what-can-you-do-with-postgresql-and-json/
Related
I have a column named params in a table named reports which contains JSON.
I need to find which rows contain the text 'authVar' anywhere in the JSON array. I don't know the path or level in which the text could appear.
I want to just search through the JSON with a standard like operator.
Something like:
SELECT * FROM reports
WHERE params LIKE '%authVar%'
I have searched and googled and read the Postgres docs. I don't understand the JSON data type very well, and figure I am missing something easy.
The JSON looks something like this.
[
{
"tileId":18811,
"Params":{
"data":[
{
"name":"Week Ending",
"color":"#27B5E1",
"report":"report1",
"locations":{
"c1":0,
"c2":0,
"r1":"authVar",
"r2":66
}
}
]
}
}
]
In Postgres 11 or earlier it is possible to recursively walk through an unknown json structure, but it would be rather complex and costly. I would propose the brute force method which should work well:
select *
from reports
where params::text like '%authVar%';
-- or
-- where params::text like '%"authVar"%';
-- if you are looking for the exact value
The query is very fast but may return unexpected extra rows in cases when the searched string is a part of one of the keys.
In Postgres 12+ the recursive searching in JSONB is pretty comfortable with the new feature of jsonpath.
Find a string value containing authVar:
select *
from reports
where jsonb_path_exists(params, '$.** ? (#.type() == "string" && # like_regex "authVar")')
The jsonpath:
$.** find any value at any level (recursive processing)
? where
#.type() == "string" value is string
&& and
# like_regex "authVar" value contains 'authVar'
Or find the exact value:
select *
from reports
where jsonb_path_exists(params, '$.** ? (# == "authVar")')
Read in the documentation:
The SQL/JSON Path Language
jsonpath Type
In my database table I have a column named data and that column's type is jsonb. Here is a sample json of the column.
{"query": {"end-date": "2016-01-31", "start-date": "2016-01-01", "max-results": 1000, "start-index": 1 }}
This is the result in a formal format.
{
"query":{
"end-date":"2016-01-31",
"start-date":"2016-01-01",
"max-results":1000,
"start-index":1
}
}
I need to get the data from the 'start date' inside the 'query' element. How get the data from the start date from a pgsql query
You can use the Postgres in-built function named 'json_extract_path'. Document.
The first parameter in this function is the column name, the second parameter is JSON root element and the third parameter is the key name of which you want to get data.
select json_extract_path(data::json,'query','start-date') as test FROM "schema".tbl_name
{
"Actor": {
"knownlanguages": [
"English"
]
}
}
This JSON is stored in JSON columntype of MySQL with name data.
My question is how to check whether knownlanguages key contains value English from JSON datatype of MySQL using query?
Easy:
SELECT * FROM table WHERE JSON_CONTAINS(json, '"English"', "$.Actor.knownlanguages")
or (depending on what you have to do):
SELECT JSON_CONTAINS(json, '"English"', "$.Actor.knownlanguages") FROM table
reference: https://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html
you can use like keyword with wildcard %
SELECT * FROM table where data like "%English%"
NOTE:
this won't search in JSON field knownlanguages, but in column data
I have a column of text type be contain JSON value.
{
"customer": [
{
"details": {
"customer1": {
"name": "john",
"addresses": {
"address1": {
"line1": "xyz",
"line2": "pqr"
},
"address2": {
"line1": "abc",
"line2": "efg"
}
}
}
"customer2": {
"name": "robin",
"addresses": {
"address1": null
}
}
}
}
]
}
How can I extract 'address1' JSON field of column with query?
First I am trying to fetch JSON value then I will go with parsing.
SELECT JSON customer from text_column;
With my query, I get following error.
com.datastax.driver.core.exceptions.SyntaxError: line 1:12 no viable
alternative at input 'customer' (SELECT [JSON] customer...)
com.datastax.driver.core.exceptions.SyntaxError: line 1:12 no viable
alternative at input 'customer' (SELECT [JSON] customer...)
Cassandra version 2.1.13
You can't use SELECT JSON in Cassandra v2.1.x CQL v3.2.x
For Cassandra v2.1.x CQL v3.2.x :
The only supported operation after SELECT are :
DISTINCT
COUNT (*)
COUNT (1)
column_name AS new_name
WRITETIME (column_name)
TTL (column_name)
dateOf(), now(), minTimeuuid(), maxTimeuuid(), unixTimestampOf(), typeAsBlob() and blobAsType()
In Cassandra v2.2.x CQL v3.3.x Introduce : SELECT JSON
With SELECT statements, the new JSON keyword can be used to return each row as a single JSON encoded map. The remainder of the SELECT statment behavior is the same.
The result map keys are the same as the column names in a normal result set. For example, a statement like “SELECT JSON a, ttl(b) FROM ...” would result in a map with keys "a" and "ttl(b)". However, this is one notable exception: for symmetry with INSERT JSON behavior, case-sensitive column names with upper-case letters will be surrounded with double quotes. For example, “SELECT JSON myColumn FROM ...” would result in a map key "\"myColumn\"" (note the escaped quotes).
The map values will JSON-encoded representations (as described below) of the result set values.
If your Cassandra version is 2.1x and below, you can use the Python-based approach.
Write a python script using Cassandra-Python API
Here you have to get your row first and then use python json's loads method, which will convert your json text column value into JSON object which will be dict in Python. Then you can play around with Python dictionaries and extract your required nested keys. See the below code snippet.
from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider
import json
if __name__ == '__main__':
auth_provider = PlainTextAuthProvider(username='xxxx', password='xxxx')
cluster = Cluster(['0.0.0.0'],
port=9042, auth_provider=auth_provider)
session = cluster.connect("keyspace_name")
print("session created successfully")
rows = session.execute('select * from user limit 10')
for user_row in rows:
customer_dict = json.loads(user_row.customer)
print(customer_dict().keys()
I have a table item with a field called data of type JSONB. I would like to query all items that have text that equals 'Super'. I am trying to do this currently by doing this:
Item.objects.filter(Q(data__areas__texts__text='Super'))
Django debug toolbar is reporting the query used for this is:
WHERE "item"."data" #> ARRAY['areas', 'texts', 'text'] = '"Super"'
But I'm not getting back any matching results. How can I query this using Django? If it's not possible in Django, then how can I query this in Postgresql?
Here's an example of the contents of the data field:
{
"areas": [
{
"texts": [
{
"text": "Super"
}
]
},
{
"texts": [
{
"text": "Duper"
}
]
}
]
}
try Item.objects.filter(data__areas__0__texts__0__text='Super')
it is not exact answer, but it can clarify some jsonb filter features, also read django docs
I am not sure what you want to achieve with this structure, but I was able to get the desired result only with strange raw query, it can look like this:
Item.objects.raw("SELECT id, data FROM (SELECT id, data, jsonb_array_elements(\"table_name\".\"data\" #> '{areas}') as areas_data from \"table_name\") foo WHERE areas_data #> '{texts}' #> '[{\"text\": \"Super\"}]'")
Dont forget to change table_name in query (in your case it should be yourappname_item).
Not sure you can use this query in real programs, but it probably can help you to find a way for a better solution.
Also, there is very good intro to jsonb query syntax
Hope it will help you