I'm trying out generated column with postgres-12. I need to create a table with generated column with JSON data. I'm going to receive "name" field as key there . However, while doing so - I got below error:
postgres=# create table json_tab2 (data jsonb ,
postgres(# "json_tab2.pname" text generated always as (data ->> "name" ) stored
postgres(# );
ERROR: column "name" does not exist
LINE 2: ...on_tab2.pname" text generated always as (data ->> "name" ) ...
After this: I tried to alter existing table- because that has value into json data for generated column - so it should be able to identify "name" now. This time I ran below:
postgres=# alter table json_tab add column Pname text generated always as (data ->> "name") stored
;
ERROR: column "name" does not exist
However, "name" has value here:
data
-------------------------------------------------
{"age": 31, "city": "New York", "name": "John"}
I'm unable to understand - what I'm doing wrong here
The righthand side of the ->> operator should be a value. In this case, since it's a string, you need to surround it with single quotes ('):
create table json_tab2 (
data jsonb,
pname text generated always as (data ->> 'name') stored
-- Here ---------------------------------^----^
);
Related
I work with Postgres db.
For example - there is a table
CREATE TABLE public.json_objects(id serial primary key, objects text);
it stores such an arrays of json
INSERT INTO public.json_objects (objects) VALUES ('[{"name":"Ivan"}]'), ('[{"name":"Petr"}, "surname":"Petrov"}]'), ('[{"form":"OOO"}, {"city":"Kizema"}]');
How can I replace the attribute "name" with "first name" or "surname" with "second name" everywhere?
I am using update with the select - subquery.
In this case, a replacement will occur, but if the attribute does not exist in the json object, then it will be added to the json with a null value (and this should not be)
WITH updated_table AS (SELECT id, jsonb_agg(new_field_json) as new_fields_json
FROM (SELECT id, jsonb_array_elements(json_objects.objects::jsonb) - 'name' || jsonb_build_object('first name', jsonb_array_elements(json_objects.objects::jsonb) -> 'name') new_field_json FROM public.json_objects) r group by id) UPDATE public.json_objects SET objects = updated_table.new_fields_json FROM updated_table where json_objects.id = updated_table.id
This seems to be a single operation, so you can just use the regexp_replace function to replace the key
update table_1 set objects = regexp_replace(objects, '(\"name"+)', '"first name"');
update table_1 set objects = regexp_replace(objects, '(\"surname"+)', '"second name"')
Demo in dbfiddle
I am migrating data from a "csv" file into a newly created table named fortune500. the code is shown below
CREATE TABLE "fortune500"(
"id" SERIAL,
"rank" INTEGER,
"title" VARCHAR PRIMARY KEY,
"name" VARCHAR,
"ticker" CHAR(5),
"url" VARCHAR,
"hq" VARCHAR,
"sector" VARCHAR,
"industry" VARCHAR,
"employees" INTEGER,
"revenues" INTEGER,
"revenues_change" REAL,
"profits" NUMERIC,
"profits_change" REAL,
"assets" NUMERIC,
"equity" NUMERIC
);
Then I wanted to migrate data from a csv file using the below code:
COPY "fortune500"("rank", "title", "name", "ticker", "url", "hq", "sector", "industry", "employees",
"revenues", "revenues_change", "profits", "profits_change", "assets", "equity")
FROM 'C:\Users\Yasser A.RahmAN\Desktop\SQL for Business Analytics\fortune.csv'
DELIMITER ','
CSV HEADER;
But I got the below error message due to NA values in one of the columns.
ERROR: invalid input syntax for type real: "NA"
CONTEXT: COPY fortune500, line 12, column profits_change: "NA"
SQL state: 22P02
So how can I get rid of 'NA' values while migrating the data?
Consider using a staging table that would not have restrictive data types and then do your transformations and insert into the final table after the data had been loaded into staging. This is known as ELT (Extract - Load - Transform) approach. You could also use some external tools to implement an ETL process, and do the transformation in that tool, before it reaches your database.
In your case, an ELT approach would be to first create a table with all text types, load that table and then insert into your final table, casting the text values into appropriate types, either filtering out the values that cannot be casted or inserting NULLs, or maybe 0, where that cast can't be made - depending on your requirements. For example you'd filter out rows where profits_change = 'NA' (or better, WHERE NOT (profits_change ~ '^\d+\.?\d+$') to check for a numeric value, or you'd insert NULL or 0:
CASE
WHEN profits_change ~ '^\d+\.?\d+$'
THEN profits_change::real
ELSE NULL -- or 0, depending what you need
END
You'd perform this kind of validation for all fields.
Alternatively, if it's a one off thing - just edit your CSV before importing.
i have the following table schema:
i want to convert the items column into a json string but the output of TO_JSON_STRING isn't what i need.
when i run this query i get:
SELECT id, store, TO_JSON_STRING(items) AS items_json
FROM nested_array_example
but what i need is items_json to be:
{"table": "3", "lamp": "7", "swedish_thing": "729"}
is there a way to do that in bigquery?
here is the query to generate the table's data:
INSERT INTO `project_name.data_seT_name.nested_array_example` (store, items, id)
VALUES ("ikea", [("table","3"),("lamp","7"),("swedish_thing",'729'),("swedish_thing_made_in_china",'5723')], '1')
Consider below approach
select id, store,
( select '{' || string_agg(format('"%s": "%s"', name, value)) || '}'
from t.items
) items_json
from `project_name.data_seT_name.nested_array_example` t
if applied to sample data from your question - output is
I am trying to upsert into a table with jsonb field based on multiple json properties in the jsonb field using below query
insert into testtable(data) values('{
"key": "Key",
"id": "350B79AD",
"value": "Custom"
}')
On conflict(data ->>'key',data ->>'id')
do update set data =data || '{"value":"Custom"}'
WHERE data ->> 'key' ='Key' and data ->> 'appid'='350B79AD'
Above query throws error as below
ERROR: syntax error at or near "->>"
LINE 8: On conflict(data ->>'key',data ->>'id')
am I missing something obvious here?
I suppose you want to insert unique id and key combination value into the table. Then you need a unique constraint for them :
create unique index on testtable ( (data->>'key'), (data->>'id') );
and also use extra parentheses for the on conflict clause as tuple :
on conflict( (data->>'key'), (data->>'id') )
and qualify the jsonb column name ( data ) by table name (testtable) whenever you meet after do update set or after where clauses as testtable.data. So, convert your statement to :
insert into testtable(data) values('{
"key": "Key",
"id": "350B79AD",
"value": "Custom1"
}')
on conflict( (data->>'key'), (data->>'id') )
do update set data = testtable.data || '{"value":"Custom2"}'
where testtable.data ->> 'key' ='Key' and testtable.data ->> 'id'='350B79AD';
btw, data ->> 'appid'='350B79AD' converted to data ->> 'id'='350B79AD' ( appid -> id )
Demo
I am trying to adapt the Audit trigger to use JSONB instead of hstore. This function stores all inserts/updates/deletes in a separate table.
The trigger has 2 interesting fields : row_data (contains the OLD.* values) and changed_fields (contains only the modified fields/values).
I have trouble converting this part.
In the original function, we have the following code :
audit_row.row_data = hstore(OLD.*);
audit_row.changed_fields = (hstore(NEW.*) - audit_row.row_data);
In my implementation, row_data and changed_fields are of type JSONB
In the documentation, the "-" operator will match on keys only and I obviously need to match on both key AND value.
As an example, if the OLD value is this :
select jsonb_object('{field1,1,field2,a string,field3,TRUE}');
jsonb_object
---------------------------------------------------------
{"field1": "1", "field2": "a string", "field3": "TRUE"}
and only field2 was updated, I need to see this :
?column?
------------------------
{"field2": "a string"}
which I would get with this query :
select jsonb_object('{field1,1,field2,a string,field3,TRUE}')
#- '{field1}'
#- '{field3}';
Is there an elegant way to do this (like how it's done with hstore) or should I keep the hstore implementation and convert changed_fields to JSONB (with everything seen as text) ?
I could also loop on all fields in NEW and add them to changed_fields if a match could not be found but how to do this inside a function ?