I need to allocate a same unique id (batchid) for each row inserted in a BD during a batch execution as illustrated below.
| id | batchid |
| -- | ------- |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 2 |
| 6 | 3 |
Was wondering if there is an automated way to do it with jpa annotation, like with a sequence ?
Did it for now this way:
#Repository
public interface SeqRepository extends JpaRepository<CsvEntity, Long> {
#Query(value = "SELECT nextval('batch_id_seq')", nativeQuery = true)
Integer getNextBatchId();
}
schema.sql
CREATE SEQUENCE IF NOT EXISTS batch_id_seq
INCREMENT 1
START 1;
Related
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)
I'm trying to get a list of records from a table, where the PK is not in a composite table. If you see consider below table, I'm trying to get all candidates that are not in a pool, so in this case I should get only Eric.
+-------------+ +-------------+
| candidates | | pools |
+-------------+ +-------------+
| id | name | | id | name |
+----+--------| +----+--------|
| 1 | John | | 1 | Pool A |
| 2 | Richard| | 2 | Pool B |
| 3 | Eric | | 3 | Pool C |
+----+--------+ +----+--------+
+--------------------------+
| candidate_pools |
+--------------------------+
| pool_id | candidate_id |
+---------+----------------|
| 1 | 1 |
| 1 | 2 |
| 3 | 2 |
| 2 | 1 |
+---------+----------------+
I've found this answer: https://laracasts.com/discuss/channels/eloquent/get-records-collection-if-not-exists-in-another-table
$crashedCarIds = CrashedCar::pluck('car_id')->all();
$cars = Car::whereNotIn('id', $crashedCarIds)->select(...)->get();
Which should work, however it seems extremely inefficient in our fairly big and rapidly growing database, on a page that is accessed often by a lot of people.
In normal MySQL you would do something like this:
WHERE candidates.id NOT IN
( SELECT candidate_id
FROM candidate_pools
LEFT JOIN pools
ON candidate_pools.pool_id = pool.id
)
Note: The tables are just a simple illustration, but the actual database set-up and queries are a lot bigger.
I managed to do it using scope, like this:
public function scopeNotInPool($query) {
$query->whereNotIn('candidate_id', function ($query) {
$query->select('candidate_id')
->from('candidate_pool')
->join('pool', function ($join) {
$join->on('pool.id', '=', 'candidate_pool.pool_id');
}
)
;
});
return $query;
}
Then call it like:
$candidates = Models\Candidate::notInPool()->get();
I'd like to know if there is a way to include row numbers (basically telling me how many records I'm getting back from a database query).
I have the following SQL query
SELECT w.widget_id, w.class_id, wg.name classname, wg.label AS classgroup, c.label, c.seq,
g.name AS group, p.name, p.type, CASE WHEN v.value IS NOT NULL THEN v.value WHEN g2p.value IS NOT NULL THEN g2p.value ELSE p.value END AS value
FROM widgets_to_categories w
INNER JOIN widget_classes c ON w.class_id = c.class_id
JOIN classes_to_param_groups t2g ON c.class_id = t2g.class_id
JOIN widget_groups g ON t2g.group_id = g.group_id
JOIN param_groups_to_params g2p ON t2g.group_id = g2p.group_id
JOIN provisioning_params p ON g2p.param_id = p.param_id
INNER JOIN widget_cat_groups wg ON c.class_group_id = wg.class_group_id
LEFT JOIN widget_values v ON(w.widget_id=v.device_id AND p.param_id=v.param_id AND g.name=v.group_name )
WHERE w.widget_id=8 ORDER BY c.class_id ASC
And it returns data like:
widget_id | class_id | classname | classgroup | label | seq | group | name | type | value
8 | 1 | toy | group A | test label | 1 | toy | reg | text | af
8 | 1 | toy | group A | test label | 1 | reg2 | fall | text | 25327
8 | 1 | toy | group A | test label | 1 | reg2 | pd | text | dvaa
8 | 1 | toy | group A | test label | 1 | reg2 | ext | text | 28235
8 | 1 | toy | group A | test label | 1 | reg1 | ext | text | 28230
8 | 1 | toy | group A | test label | 1 | toy | meec | text | 094F22DE501
8 | 1 | toy | group A | test label | 1 | toy | mmap | text | 0|
8 | 1 | toy | group A | test label | 1 | reg1 | fna | text | 26014
8 | 1 | toy | group A | test label | 1 | reg1 | fall | text | t-123
8 | 1 | toy | group A | test label | 1 | toy | uen | boolean | false
8 | 1 | toy | group A | test label | 1 | toy | adminpd |
I'd like to know if there's a way to have the database auto generate and return another column that is just an identifier for the row, like so:
id |widget_id | class_id | classname | classgroup | label | seq | group | name | type | value
1 | 8 | 1 | toy | group A | test label | 1 | toy | reg | text | af
2 | 8 | 1 | toy | group A | test label | 1 | reg2 | fall | text | 25327
3 | 8 | 1 | toy | group A | test label | 1 | reg2 | pd | text | dvaa
4 | 8 | 1 | toy | group A | test label | 1 | reg2 | ext | text | 28235
5 | 8 | 1 | toy | group A | test label | 1 | reg1 | ext | text | 28230
6 | 8 | 1 | toy | group A | test label | 1 | toy | meec | text | 094F22DE501
7 | 8 | 1 | toy | group A | test label | 1 | toy | mmap | text | 0|
8 | 8 | 1 | toy | group A | test label | 1 | reg1 | fna | text | 26014
9 | 8 | 1 | toy | group A | test label | 1 | reg1 | fall | text | t-123
10 | 8 | 1 | toy | group A | test label | 1 | toy | uen | boolean | false
11 | 8 | 1 | toy | group A | test label | 1 | toy | adminpd | boolean | false
I think I can do this by selecting into a temporary table.. I haven't figured out the syntax on how to do it yet... But I'm also wondering if there's another simpler way.
Once I get the data back from the database, having this ID field makes it eaiser to manipulate.
Thanks.
You can use the row_number window function to keep track of each row number.
Like so:
create table foo
(
id serial,
val text
);
INSERT INTO foo (val)
VALUES ('One'), ('Two'), ('Three');
SELECT f.*, row_number() OVER(ORDER BY val)
FROM foo AS f
ORDER BY val;
Here's an SQL Fiddle which shows this:
http://sqlfiddle.com/#!15/0c434/2
Additional options:
You could count the result with a query of the form:
SELECT count(*)
FROM
(
SELECT *
FROM foo
);
Or you may be able to get the row count back as part of the Postgres library you're using. For example, psycopg2 (Python) and DBI (Perl) allow for this (with some caveats). The library you're using may offer something similar.