When I make the query:
"select * from asset a where (a.login_id = $1) and (a.status = 'pub')";
I get back the expected result:
{
id: 23f8jfj8gh2,
name: 'Asset1',
status: 'pub',
create_date: 2020-11-12T07:00:00.000Z,
...
}
But when I add a left join onto the query like this:
"select * from asset a left join asset_image i on (a.id = i.asset_id) where (a.login_id = $1) and (a.status = 'pub')";
I get back:
{
id: null, <---- THIS NULL VALUE for the asset id
name: 'Asset1',
status: 'pub',
create_date: 2020-11-12T07:00:00.000Z,
...
asset_id: null,
orig_name: null,
mimetype: null,
created: null
}
I am new to SQL, and I have looked at the docs for left joins, but I can't seem to figure out exactly where this is going wrong. Any help would be much appreciated! Thanks.
If the asset_image table contains its own column with the name of id when your query gets no match between (a.id = i.asset_id) it will overwrite the id field with null.
You may need to define each tables id column with a more unique name eg.
asset_id to replace id in the asset table
image_id to replace id in the asset_image table
Your problem is probably the * in SELECT *, which is something that you should always avoid in code.
If the table asset_image also has a column named id, your result set will contain two columns named id. You are probably looking at the wrong one.
Using SELECT * gives you no control over the columns you get in the result set, their name and their order. You should use an explicit column list and give columns with the same name in both tables an alias that allows you to disambiguate them.
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 apologize if this is a simple question - I had some trouble even formatting the question when I was trying to Google for help!
In one of the tables I am working with, there's data value that looks like below:
Invoice ID
Status
Product List
1234
Processed
[{"product_id":463153},{"product_id":463165},{"product_id":463177},{"pid":463218}]
I want to count how many products each order has purchased. What is the proper syntax and way to count the values under "Product List" column? I'm aware that count() is wrong, and I need to maybe extract the data from the string value.
select invoice_id, count(Product_list)
from quote_table
where status = 'processed'
group by invoice_id
You can use a JSON function named: json_array_length and cast this column like a JSON data type (as long as possible), for example:
select invoice_id, json_array_length(Product_list::json) as count
from quote_table
where status = 'processed'
group by invoice_id;
invoice_id | count
------------+-------
1234 | 4
(1 row)
If you need to count a specific property of the json column, you can use the query below.
This query solves the problem by using create type, json_populate_recordset and subquery to count product_id inside json data.
drop type if exists count_product;
create type count_product as (product_id int);
select
t.invoice_id,
t.status,
(
select count(*) from json_populate_recordset(
null::count_product,
t.Product_list
)
where product_id is not null
) as count_produto_id
from (
-- symbolic data to use in query
select
1234 as invoice_id,
'processed' as status,
'[{"product_id":463153},{"product_id":463165},{"product_id":463177},{"pid":463218}]'::json as Product_list
) as t
I am having a problem when trying to select rows from a Postgres view filtering by name.
The result from the query should be a company in company_portfolio named 'any company 2'. However, instead of returning the company, it returns nothing. By nothing I mean an empty array of companies instead of an array containing the company with the name 'any company 2'.
I have created a Postgres view that looks something like this:
CREATE OR REPLACE view company_portfolio as
SELECT company.id,
company.name,
...
FROM "Company" company
LEFT JOIN
(SELECT DISTINCT ... FROM
(SELECT DISTINCT ... FROM "Contract") a
GROUP BY 1) as smpLists
ON company.... = smpLists...
I have created a company with the name: 'any company 2'.
I am querying the table with my prisma client like this:
if (params.name) {
filters = `${filters} AND "name" = '${params.name}'`;
}
return this.prisma.$queryRaw(
`
SELECT * FROM "company_portfolio"
WHERE id IS NOT NULL ${filters}
ORDER BY ${orderBy}
LIMIT ${params.limit}
OFFSET ${params.offset}
`
);
So the end query is like this:
SELECT * FROM "company_portfolio"
WHERE id IS NOT NULL AND name = 'any company 2'
ORDER BY name ASC
LIMIT 1
OFFSET 1
It is returning an empty array, so it is not properly selected the company with the name = 'any company 2'.
I have executed a similar query on the database directly and it returns the desired company.
Does anyone spot what could be wrong here?
Solved it.
I was setting an offset = 1 and a limit = 1. This returns the second row from the select query result.
Since there was only 1 record meeting the criteria of the select query, there was not a second record, thus I was seeing an empty array.
I am creating a viewer for PostgreSQL. My SQL needs to sort on the type that is normal for that column. Take for example:
Table:
CREATE TABLE contacts (id serial primary key, name varchar)
SQL:
SELECT id::text FROM contacts ORDER BY id;
Gives:
1
10
100
2
Ok, so I change the SQL to:
SELECT id::text FROM contacts ORDER BY id::regtype;
Which reults in:
1
2
10
100
Nice! But now I try:
SELECT name::text FROM contacts ORDER BY name::regtype;
Which results in:
invalid type name "my first string"
Google is no help. Any ideas? Thanks
Repeat: the error is not my problem. My problem is that I need to convert each column to text, but order by the normal type for that column.
regtype is a object identifier type and there is no reason to use it when you are not referring to system objects (types in this case).
You should cast the column to integer in the first query:
SELECT id::text
FROM contacts
ORDER BY id::integer;
You can use qualified column names in the order by clause. This will work with any sortable type of column.
SELECT id::text
FROM contacts
ORDER BY contacts.id;
So, I found two ways to accomplish this. The first is the solution #klin provided by querying the table and then constructing my own query based on the data. An untested psycopg2 example:
c = conn.cursor()
c.execute("SELECT * FROM contacts LIMIT 1")
select_sql = "SELECT "
for row in c.description:
if row.name == "my_sort_column":
if row.type_code == 23:
sort_by_sql = row.name + "::integer "
else:
sort_by_sql = row.name + "::text "
c.execute("SELECT * FROM contacts " + sort_by_sql)
A more elegant way would be like this:
SELECT id::text AS _id, name::text AS _name AS n FROM contacts ORDER BY id
This uses aliases so that ORDER BY still picks up the original data. The last option is more readable if nothing else.
I want to add a denormalized table for some data of a gtfs-feed. For that I created a new table:
CREATE TABLE denormalized_trips (
stops_coords json NOT NULL,
stops_object json NOT NULL,
agency_key text NOT NULL,
trip_id text NOT NULL,
route_id text NOT NULL,
service_id text NOT NULL,
shape_id text,
route_color text,
route_long_name text,
route_desc text,
direction_id text
);
CREATE INDEX denormalized_trips_index ON denormalized_trips (agency_key, trip_id);
CREATE UNIQUE INDEX denormalized_trips_index ON denormalized_trips (agency_key, route_id);
Now I want to transfer data from one table to the other via an insert statement. The statement is rather complex.
INSERT INTO denormalized_trips
SELECT
trps.stops_coords,
trps.stops_object,
trps.trip_id,
trps.service_id,
trps.route_id,
trps.direction_id,
trps.agency_key,
trps.shape_id,
trps.route_color,
trps.route_long_name,
trps.route_desc
FROM (
SELECT
array_to_json(ARRAY_AGG(array[stop_lat, stop_lon])) AS stops_coords,
array_to_json(ARRAY_AGG(array[
stops.stop_id,
CAST ( stop_times.stop_sequence AS TEXT ),
stops.stop_name,
stop_times.departure_time,
CAST ( stop_times.departure_time_seconds AS TEXT ),
stop_times.arrival_time,
CAST ( stop_times.arrival_time_seconds AS TEXT )
])) AS stops_object,
trips.trip_id,
trips.service_id,
trips.direction_id,
trips.agency_key,
trips.shape_id,
routes.route_id,
routes.route_color,
routes.route_long_name,
routes.route_desc
FROM gtfs_stop_times AS stop_times
INNER JOIN gtfs_trips AS trips
ON trips.trip_id = stop_times.trip_id AND trips.agency_key = stop_times.agency_key
INNER JOIN gtfs_routes AS routes ON trips.agency_key = routes.agency_key AND routes.route_id = trips.route_id
INNER JOIN gtfs_stops AS stops
ON stops.stop_id = stop_times.stop_id
AND stops.agency_key = stop_times.agency_key
AND NOT EXISTS (
SELECT 0
FROM denormalized_max_stop_sequence AS max
WHERE max.agency_key = stop_times.agency_key
AND max.trip_id = stop_times.trip_id
AND max.trip_max = stop_times.stop_sequence
)
GROUP BY
trips.trip_id,
trips.service_id,
trips.direction_id,
trips.agency_key,
trips.shape_id,
routes.route_id,
routes.route_color,
routes.route_long_name,
routes.route_desc
) as trps
If I just run the inner select statement I will get the right results. They look something like this: (screenshot does not show all tables because it's too long)
But if I execute the insert statement and display the content of the table i will get something like this:
As you may notice the contents are not inserted into the right columns of the table. The agency_key now has the values of the trip_id and the direction_id is now the service_id (and there are more tables that are messed up).
So my question is what am I doing wrong that my insert statement inserts the contents into the wrong columns of the newly created table?
Thanks for your help.
Postgres, by default, will insert your values in the order the columns are declared in the table; it has nothing to do with what your columns are named in the query.
https://www.postgresql.org/docs/9.5/static/sql-insert.html
If no list of column names is given at all, the default is all the columns of the table in their declared order; or the first N column names, if there are only N columns supplied by the VALUES clause or query.
You can alter your insert to declare the order of the columns you're inserting, or you can change the order of your select to match the order of columns in the table.