I have a table with the following schema in a SQL Azure DB (2019 compat level):
CREATE TABLE dbo.Properties
(
PropertyId int,
PropertyName nvarchar(100),
PropertyValue nvarchar(1000)
)
I'd like to take the data within this table and turn it into JSON using the value within the PropertyName column as the name of the JSON property, and obviously the PropertyValue value as the JSON property value.
EDIT 12/10/2021:
Importantly, the values within the PropertyName column will not be predictable ahead of time.
For example, consider this data in the table (3 rows):
1, "Color", "Blue"
1, "Name", "John"
1, "Cost", 5
The above would be turned into the following JSON:
{"Color":"Blue", "Name":"John", "Cost":5}
I'm obviously able to do this with a STRING_AGG function like the following:
SELECT '{' + STRING_AGG( '"' + p.PropertyName + '": ''' + p.PropertyValue,''',')
WITHIN GROUP (ORDER BY p.PropertyName) + '}' AS MyJson
FROM dbo.Properties p
GROUP BY p.Id
But I was hoping to use one of the build in JSON functions rather than hack together a big string.
FOR JSON AUTO works from the column names, so one method to get your desired result would be to PIVOT the property names into columns. For example:
SELECT Color, [Name], Cost
FROM dbo.Properties
PIVOT ( MAX( PropertyValue ) For PropertyName In ( [Color], [Name], Cost ) ) pvt
FOR JSON AUTO;
My results:
Of course this is only convenient if your JSON attributes / column names are always known and it's a simple example. For more complex examples, you are probably looking at dynamic pivot, or dynamic SQL and your STRING_AGG example isn't so bad.
I have a varchar(255) field within a source table and the following contents:
50339 My great example
2020002 Next ID but different title
202020 Here we go
Now I am processing the data and do an insert select query on it. From this field I would need the INT number at the beginning of the field. IT IS followed by 2 spaces and a text with var length, this text is what I need as well but for another field. In General I want to to put text and ID in two fields which are now in one.
I tried to grab it like this:
SELECT STATUS REGEXP '^(/d{6,8}) ' FROM products_test WHERE STATUS is not null
But then I learned that in MySQL 5.x there are no regexp within the SELECT statement.
How could I seperate those values within a single select statment, so I can use it in my INSERT SELECT?
From the correct solution of user slaakso, resulted another related problem since somtimes the STATUS field is empty which then results in only one insert, but in case there is a value I split it into two fields. So the count does not match.
My case statement with his solution somehow contains a syntax problem:
CASE STATUS WHEN ''
THEN(
NULL,
NULL
)
ELSE(
cast(STATUS as unsigned),
substring(STATUS, locate(' ', STATUS)+3)
)
END
You can do following. Note that you need to treat the columns separately:
select
if(ifnull(status, '')!='', cast(status as unsigned), null),
if(ifnull(status, '')!='', substring(status, locate(' ', status)+2), null)
from products_test;
See db-fiddle
(This is an extension to this question, but my reputation is too low to comment or ask more questions on that topic...)
We work on bigquery, hence limited in importing packages or using other languages. And, as per the link above, js is a solution, but not what I'm looking for here. I implemented it in js, and it was too slow for our needs.
Suppose one of our columns is a string that look like this (array of json):
[{"location":[22.99902,66.000],"t":1},{"location":[55.32168,140.556],"t":2},{"location":[85.0002,20.0055],"t":3}]
I want to extract from the column the json for which "t":2
Where:
some columns don't have elements "t":2
Some columns have several elements "t":2
The number of json elements in each string can change
element "t":2 is not always in second position.
I don't know regexp well enough for this. We tried regexp_extract with this pattern: r'(\{.*?\"t\":2.*?\})')), but that doesn't work. It extracts everything that precedes "t":2, including the json for "t":2. We only want the json of element "t":2.
Could you advise a regexp pattern that would work?
EDIT:
I have a preference for a solution that gives me 1 match. Suppose I have this string:
[{"location":[22.99902,66.000],"t":1},{"location":[55.32168,140.556],"t":2},{"location":[55.33,141.785],"t":2}],
I would prefer receiving only 1 answer, the first one.
In that case perhaps regexp is less appropriate, but I'm really not sure?
How about this:
(?<=\{)(?=.*?\"t\"\s*:\s*2).*?(?=\})
As seen here
There is another solution but it is not regexp based (as I had originally asked). So this should not count as the final answer to my own question, nonetheless could be useful.
It is based on a split of the string in array and then chosing the element in the array that satisfies my needs.
Steps:
transform the string into something better for splits (using '|' as seperator):
replace(replace(replace(my_field,'},{','}|{'),'[{','{'),'}]','}')
split it using split(), which yields an array of strings (each one a json element)
find the relevant element ("t":2) - in my case, the first one is good enough, so I limit the query to 1: array( select data from unnest(split(replace(replace(replace(my_field,'},{','}|{'),'[{','{'),'}]','}'),'|')) as data where data like '%"t":2%' limit 1)
Convert that into a useable string with array_to_string() and use json_extract on that string to extract the relevant info from the element that I need (say for example, location coordinate x).
So putting it all together:
round(safe_cast(json_extract(array_to_string(array( select data from unnest(split(replace(replace(replace(my_field,'},{','}|{'),'[{','{'),'}]','}'),'|')) as data where data like '%"t":2%' limit 1),''),'$.location[0]') as float64),3) loc_x
May 1st, 2020 Update
A new function, JSON_EXTRACT_ARRAY, has been just added to the list of JSON
functions. This function allows you to extract the contents of a JSON document as
a string array.
so in below you can replace use of json2array UDF with just in-built function JSON_EXTRACT_ARRAY as in below example
#standardSQL
SELECT id,
(
SELECT x
FROM UNNEST(JSON_EXTRACT_ARRAY(json, '$')) x
WHERE JSON_EXTRACT_SCALAR(x, '$.t') = '2'
) extracted
FROM `project.dataset.table`
==============
Below is for BigQuery Standard SQL
#standardSQL
CREATE TEMP FUNCTION json2array(json STRING)
RETURNS ARRAY<STRING>
LANGUAGE js AS """
return JSON.parse(json).map(x=>JSON.stringify(x));
""";
SELECT id,
(
SELECT x
FROM UNNEST(json2array(JSON_EXTRACT(json, '$'))) x
WHERE JSON_EXTRACT_SCALAR(x, '$.t') = '2'
) extracted
FROM `project.dataset.table`
You can test, play with above using dummy data as in below example
#standardSQL
CREATE TEMP FUNCTION json2array(json STRING)
RETURNS ARRAY<STRING>
LANGUAGE js AS """
return JSON.parse(json).map(x=>JSON.stringify(x));
""";
WITH `project.dataset.table` AS (
SELECT 1 id, '[{"location":[22.99902,66.000],"t":1},{"location":[55.32168,140.556],"t":2},{"location":[85.0002,20.0055],"t":3}]' json UNION ALL
SELECT 2, '[{"location":[22.99902,66.000],"t":11},{"location":[85.0002,20.0055],"t":13}]'
)
SELECT id,
(
SELECT x
FROM UNNEST(json2array(JSON_EXTRACT(json, '$'))) x
WHERE JSON_EXTRACT_SCALAR(x, '$.t') = '2'
) extracted
FROM `project.dataset.table`
with output
Row id extracted
1 1 {"location":[55.32168,140.556],"t":2}
2 2 null
Above assumes that there is no more than one element with "t":2 in json column. In case if there can be more than one - you should add ARRAY as below
SELECT id,
ARRAY(
SELECT x
FROM UNNEST(json2array(JSON_EXTRACT(json, '$'))) x
WHERE JSON_EXTRACT_SCALAR(x, '$.t') = '2'
) extracted
FROM `project.dataset.table`
Even though, you have posted a work around your issue. I believe this answer will be informative. You mentioned that one of the answer selected more than what you needed, I wrote the query below to reproduce your case and achieve aimed output.
WITH
data AS (
SELECT
" [{ \"location\":[22.99902,66.000]\"t\":1},{\"location\":[55.32168,140.556],\"t\":2},{\"location\":[85.0002,20.0055],\"t\":3}] " AS string_j
UNION ALL
SELECT
" [{ \"location\":[22.99902,66.000]\"t\":1},{\"location\":[55.32168,140.556],\"t\":3},{\"location\":[85.0002,20.0055],\"t\":3}] " AS string_j
UNION ALL
SELECT
" [{ \"location\":[22.99902,66.000]\"t\":1},{\"location\":[55.32168,140.556],\"t\":3},{\"location\":[85.0002,20.0055],\"t\":3}] " AS string_j
UNION ALL
SELECT
" [{ \"location\":[22.99902,66.000]\"t\":1},{\"location\":[55.32168,140.556],\"t\":3},{\"location\":[85.0002,20.0055],\"t\":3}] " AS string_j ),
refined_data AS (
SELECT
REGEXP_EXTRACT(string_j, r"\{\"\w*\"\:\[\d*\.\d*\,\d*\.\d*\]\,\"t\"\:2\}") AS desired_field
FROM
data )
SELECT
*
FROM
refined_data
WHERE
desired_field IS NOT NULL
Notice that I have used the dummy described in the temp table, populated inside the WITH method. As below:
Afterwords, in the table refined_data, I used the REGEXP_EXTRACT to extract the desired string from the column. Observe that for the rows which there is not a match expression, the output is null. Thus, the table refined_data is as follows :
As you can see, now it is just needed a simple WHERE filter to obtain the desired output, which was done in the last select.
In addition you can see the information about the regex expression I provided here.
I have some db that stores json array of objects in a column. I need to make columns out of these objects keys if object's id has certain value
My documents table is simple:
id | name | percent_split
1 | some name | [ {id: 59, share:22, value: 55},{id:58, share:40, value:33}]
I've tried some variants of the following to get the data, not mentioning making columns out of object keys:
SELECT
id, name,
(SELECT FROM documents
WHERE (
CASE WHEN JSON_VALID(percent_split) THEN
json_search(percent_split, 'one', '{"id":"59"}')
ELSE null
END)
) AS result_for_59
FROM documents
I would like to get additional columns in the result of my query
id, name, 59_share, 59_value, NN_share, NN_value
Please help :)
I could go with any language easily, but in this case I'm limited to use only MySql technology.
We made a function in mysql which has two arguments: the column_value and the value we search for:
RETURN JSON_EXTRACT(value, JSON_UNQUOTE(
REPLACE(
JSON_SEARCH(
,'one',column_value
),'.id','.share'
))
)
Then we call it inside select part of query, for every value we need:
if(json_valid(percent_split),get_share(39, percent_split),NULL) AS share39
I am accessing an array (a json object called 'choice_values') in a jsonb field, and would like to parse its contents into a comma-separated text field.
SELECT
jsonb_array_elements(doc -> 'form_values' -> '8189' -> 'choice_values')
FROM
field_data.exports;
That jsonb_array_elements function returns a "setof text", which I would like converted to a comma separated list of the array values, contained within a single field.
Thank you.
Set returning functions (like jsonb_array_elements_text()) can be called in SELECT list, but then they cannot be used in aggregate functions.
This is a good practice to call set returning functions in FROM clause, often in a lateral join like in this example:
with the_data as (
select '["alfa", "beta", "gamma"]'::jsonb as js
)
select string_agg(elem, ',')
from
the_data,
jsonb_array_elements_text(js) elem;
string_agg
-----------------
alfa,beta,gamma
(1 row)
So your query should look like this:
select string_agg(elem, ',')
from
field_data.exports,
jsonb_array_elements_text(doc -> 'form_values' -> '8189' -> 'choice_values') elem;
Using the string_agg aggregate function with a sub-select from jsonb_array_elements_text seems to work (tested on PG 9.5). Note the use of jsonb_array_elements_text, added in PostgreSQL 9.4, rather than jsonb_array_elements, from PostgreSQL 9.3.
with exports as (
select $${"form_values": {"8189": {"choice_values": ["a","b","c"]}}}$$::jsonb as doc
)
SELECT
string_agg(values, ', ')
FROM
exports, jsonb_array_elements_text(doc -> 'form_values' -> '8189' -> 'choice_values') values
GROUP BY
exports.doc;
Output:
'a, b, c'
Also see this question and its answers.
Maybe not best practice: convert the json array to text, then remove the brackets.
WITH input AS (
SELECT '["text1","text2","text3"]'::jsonb as data
)
SELECT substring(data::text,2,length(data::text)-2) FROM input
It has the advantage that it converts "in-place", not by aggregating. This could be handy if you can only access part of the query, e.g. for some synchronization tool where there's field-based conversion rules, or something like the following:
CREATE TEMP TABLE example AS (SELECT '["text1","text2","text3"]'::jsonb as data);
ALTER TABLE example ALTER COLUMN data TYPE text USING substring(data::text,2,length(data::text)-2);