So many similar questions - mainly the questions are about how to select one of the duplicates where only a single column is different, but I want to exclude all of them from a query, and only get the ones where a particular field isn't different.
I am looking for all the reference_no where the status is -1, except for those where the status is both -1 and 1 for the same reference_no, as in the table below. The query should return only row Id 4. How do I do that?
This is using SQL server 2016
| id | process_date | status | reference_no |
| --- | ------------ | ------ | ----------- |
| 1 | 12/5/22 | 1 | 789456 |
| 2 | 12/5/22 | -1 | 789456 |
| 3 | 12/5/22 | 1 | 789456 |
| 4 | 12/5/22 | 1 | 321654 |
If I understand correctly you want a not exists check
select *
from t
where status = -1
and not exists (
select * from t t2
where t2.status = 1 and t2.reference_no = t.reference_no
);
Related
My objective is getting all orders with duplicated order_number by location, that has checkout = true at least one time. But I'm having issues to translate this to Django ORM.
example of data:
| id | order_number | location_id | checkout |
|----|--------------|-------------|----------|
| 1 | 1 | 1 | true |
| 2 | 1 | 1 | true |
| 3 | 1 | 1 | false |
| 4 | 2 | 1 | true |
| 5 | 1 | 2 | true |
| 6 | 2 | 2 | false |
select count(*), order_number, location_id from orders where checkout = true group by location_id, order_number having count(*) > 1;
the expectation
| count | order_number | location_id |
|-------|--------------|-------------|
| 2 | 1 | 1 |
I already tried this, but it's not working as expected
>>> Order.objects.filter(checkout=True).values_list('order_number', 'location_id').annotate(count_order_number=Count("order_number")).filter(count_order_number__gt=1)
<QuerySet []>
I'm using
Django=3.2
postgresql
I have a dataset that is similar to this. I need to pick out the most recent metadata (greater execution time = more recent) for a client including the sum of quantities and the latest execution time and meta where the quantity > 0
| Name | Quantity | Metadata | Execution time |
| -------- | ---------|----------|----------------|
| Neil | 1 | [1,3] | 4 |
| James | 1 | [2,18] | 5 |
| Neil | 1 | [4, 1] | 6 |
| Mike | 1 | [5, 42] | 7 |
| James | -1 | Null | 8 |
| Neil | -1 | Null | 9 |
Eg the query needs to return:
| Name | Summed Quantity | Metadata | Execution time |
| -------- | ----------------|----------|----------------|
| James | 0 | [2,18] | 5 |
| Neil | 1 | [4, 1] | 6 |
| Mike | 1 | [5, 42] | 7 |
My query doesn't quite work as it's not returning the sum of the quantities correctly.
SELECT
distinct on (name) name,
(
SELECT
cast(
sum(quantity) as int
)
) as summed_quantity,
meta,
execution_time
FROM
table
where
quantity > 0
group by
name,
meta,
execution_time
order by
name,
execution_time desc;
This query gives a result of
| Name | Summed Quantity | Metadata | Execution time |
| -------- | ----------------|----------|----------------|
| James | 1 | [2,18] | 5 |
| Neil | 1 | [4, 1] | 6 |
| Mike | 1 | [5, 42] | 7 |
ie it's just taking the quantity > 0 from the where and not adding up the quantities in the sub query (i assume because of the distinct clause) I'm unsure how to fix my query to produce the desired output.
This can be achieved using window functions (hence with a single pass of the data)
select
name
, sum_qty
, metadata
, execution_time
from (
select
*
, sum(Quantity) over(partition by name) sum_qty
, row_number() over(partition by name, case when quantity > 0 then 1 else 0 end
order by Execution_time DESC) as rn
from mytable
) d
where rn = 1 and quantity > 0
order by name
result
+-------+---------+----------+----------------+
| name | sum_qty | metadata | execution_time |
+-------+---------+----------+----------------+
| James | 0 | [2,18] | 5 |
| Mike | 1 | [5,42] | 7 |
| Neil | 1 | [4,1] | 6 |
+-------+---------+----------+----------------+
db<>fiddle here
The example above can be done on a SQL Server. It is a function that performs the calculation on another table while getting the current table field Id to list data from other table, return a single value.
Question: how to do the exact thing with PostgreSQL
SELECT TOP(5) * FROM Artists;
+------------+------------------+--------------+-------------+
| ArtistId | ArtistName | ActiveFrom | CountryId |
|------------+------------------+--------------+-------------|
| 1 | Iron Maiden | 1975-12-25 | 3 |
| 2 | AC/DC | 1973-01-11 | 2 |
| 3 | Allan Holdsworth | 1969-01-01 | 3 |
| 4 | Buddy Rich | 1919-01-01 | 6 |
| 5 | Devin Townsend | 1993-01-01 | 8 |
+------------+------------------+--------------+-------------+
SELECT TOP(5) * FROM Albums;
+-----------+------------------------+---------------+------------+-----------+
| AlbumId | AlbumName | ReleaseDate | ArtistId | GenreId |
|-----------+------------------------+---------------+------------+-----------|
| 1 | Powerslave | 1984-09-03 | 1 | 1 |
| 2 | Powerage | 1978-05-05 | 2 | 1 |
| 3 | Singing Down the Lane | 1956-01-01 | 6 | 3 |
| 4 | Ziltoid the Omniscient | 2007-05-21 | 5 | 1 |
| 5 | Casualties of Cool | 2014-05-14 | 5 | 1 |
+-----------+------------------------+---------------+------------+-----------+
The function
CREATE FUNCTION [dbo].[ufn_AlbumCount] (#ArtistId int)
RETURNS smallint
AS
BEGIN
DECLARE #AlbumCount int;
SELECT #AlbumCount = COUNT(AlbumId)
FROM Albums
WHERE ArtistId = #ArtistId;
RETURN #AlbumCount;
END;
GO
Now, (at SQL Server), after update the first table fields with ALTER TABLE Artists ADD AlbumCount AS dbo.ufn_AlbumCount(ArtistId); whe can list and get the following result.
+------------+------------------+--------------+-------------+--------------+
| ArtistId | ArtistName | ActiveFrom | CountryId | AlbumCount |
|------------+------------------+--------------+-------------+--------------|
| 1 | Iron Maiden | 1975-12-25 | 3 | 5 |
| 2 | AC/DC | 1973-01-11 | 2 | 3 |
| 3 | Allan Holdsworth | 1969-01-01 | 3 | 2 |
| 4 | Buddy Rich | 1919-01-01 | 6 | 1 |
| 5 | Devin Townsend | 1993-01-01 | 8 | 3 |
| 6 | Jim Reeves | 1948-01-01 | 6 | 1 |
| 7 | Tom Jones | 1963-01-01 | 4 | 3 |
| 8 | Maroon 5 | 1994-01-01 | 6 | 0 |
| 9 | The Script | 2001-01-01 | 5 | 1 |
| 10 | Lit | 1988-06-26 | 6 | 0 |
+------------+------------------+--------------+-------------+--------------+
but how to achieve this on postgresql?
Postgres doesn't support "virtual" computed column (i.e. computed columns that are generated at runtime), so there is no exact equivalent. The most efficient solution is a view that counts this:
create view artists_with_counts
as
select a.*,
coalesce(t.album_count, 0) as album_count
from artists a
left join (
select artist_id, count(*) as album_count
from albums
group by artist_id
) t on a.artist_id = t.artist_id;
Another option is to create a function that can be used as a "virtual column" in a select - but as this is done row-by-row, this will be substantially slower than the view.
create function album_count(p_artist artists)
returns bigint
as
$$
select count(*)
from albums a
where a.artist_id = p_artist.artist_id;
$$
language sql
stable;
Then you can include this as a column:
select a.*, a.album_count
from artists a;
Using the function like that, requires to prefix the function reference with the table alias (alternatively, you can use album_count(a))
Online example
I need help with updating table from another table in Postgres Db.
Long story short we ended up with corrupted data in db, and now I need to update one table with values from another.
I have table with this data table wfc:
| step_id | command_id | commands_order |
|---------|------------|----------------|
| 1 | 1 | 0 |
| 1 | 2 | 1 |
| 1 | 3 | 2 |
| 1 | 4 | 3 |
| 1 | 1 | 0 |
| 2 | 2 | 0 |
| 2 | 3 | 1 |
| 2 | 3 | 1 |
| 2 | 4 | 3 |
and I want to update values in command_order column from another table, so I can have result like this:
| step_id | command_id | commands_order|
|---------|------------|---------------|
| 1 | 1 | 0 |
| 1 | 2 | 1 |
| 1 | 3 | 2 |
| 1 | 4 | 3 |
| 1 | 1 | 4 |
| 2 | 2 | 0 |
| 2 | 3 | 1 |
| 2 | 3 | 2 |
| 2 | 4 | 3 |
It was looking like easy task, but problem is to update rows for same command_id, it is writing same value in commands_order
SQL that I tried is:
UPDATE wfc
SET commands_order = CAST(sq.input_step_id as INTEGER)
FROM (
SELECT wfp.step_id, wfp.input_command_id, wfp.input_step_id
from wfp
order by wfp.step_id, wfp.input_step_id
) AS sq
WHERE (wfc.step_id=sq.step_id AND wfc.command_id=CAST(sq.input_command_id as INTEGER));
SQL Fiddle http://sqlfiddle.com/#!15/4efff4/4
I am pretty stuck with this, please help.
Thanks in advance.
Assuming you are trying to number the rows in the order in which they were created, and as long as you understand that ctid will chnage on update and with VACCUUM FULL, you can do the following:
select step_id, command_id, rank - 1 as command_order
from (select step_id, command_id, ctid as wfc_ctid, rank() over
(partition by step_id order by ctid)
from wfc) as wfc_ordered;
This will give you the wfc table with the ordering that you want. If you do update the original table, the ctids will change, so it's probably safer to create a copy of the table with the above query.
I have a next table sample, called userz:
+----+---------------+----------+
| id | sort_position | type |
+----+---------------+----------+
| 1 | -5 | admin |
| 2 | -3 | customer |
| 3 | 1 | customer |
| 4 | 8 | employee |
| 5 | 200 | customer |
+----+---------------+----------+
With Mysql If i want to make sort_position of all customer type to start from 0 and ++ until the last row that satisfies WHERE criteria, i can do next:
SET #i=-1;
UPDATE userz
SET sort_position=#i:=#i+1
WHERE type = "customer" ORDER BY sort_position;
and i would receive expected result:
+----+---------------+----------+
| id | sort_position | type |
+----+---------------+----------+
| 1 | -5 | admin |
| 2 | 0 | customer |
| 3 | 1 | customer |
| 4 | 8 | employee |
| 5 | 2 | customer |
+----+---------------+----------+
as you see all customers are now assigned with correct sort_position of 0,1,2
But since i'm working with postgre i need to reach same with it. What i tried so far:
DO $$
DECLARE
i integer := -1;
BEGIN
UPDATE userz
SET sort_position=#i:=#i+1
WHERE type = "customer" ORDER BY sort_position;
END $$;
and i have errors around =#i:=#i+1 , tried different formatting that i googled like =i:=i+1 but still no luck.
Try below SQL;
update userz k
set sort_position =
(select ROW_NUMBER() over(order by sort_position)-1 rnum
from userz src
where src.type ='customer'
and id = k.id)