Questions tagged [order-by]
A clause used in SQL SELECT statements to sort query results.
346
questions
1
vote
1answer
26 views
Determine Order Streak
For a particular customer, I have data returned by a query that looks like this:
OrderDate OrderCount
2020-01-12 0
2020-01-13 17
2020-01-14 22
2020-01-15 21
2020-01-16 30
2020-01-17 12
2020-...
0
votes
0answers
15 views
MySQL query help
I need a query that returns the number of liked messages and orders them by the number of likes (from most to least).
I have tried:
SELECT users.user_id,
messages.author,
messages....
1
vote
1answer
17 views
Is SELECT FOR … UPDATE *necessary* to DELETE or UPDATE multiple rows without deadlock?
Consider the following when the transaction isolation level is Read Committed (the default):
UPDATE example
SET foo = 'bar'
WHERE ...
and
DELETE FROM example
WHERE ...
Neither DELETE nor UPDATE ...
0
votes
1answer
55 views
ORDER from 2 tables to achieve a specific order returned by an API
There's an external API that returns image similarities, based on an "image ID" and a "image version" (a same image can have multiple versions).
The similarity ORDER is given by the API.
The API ...
0
votes
2answers
21 views
Can I tell postgres to use a different “collation” for an integer column?
Let's say I'm using an integer column to represent an "enum" in my application code, for a "priority" attribute.
0=low
1=medium
2=high
The app is operating for a while like that, and then I want to ...
3
votes
1answer
34 views
Why does ORDER BY NULLS LAST affect the query plan on a primary key?
Using PostgreSQL 11, I have the following table with around 450 million rows:
postgres=> \d+ sales
Table "public.sales"
...
0
votes
1answer
33 views
Ordering by field, constructed by subquery is slow
My tables (oversimplified for clarity):
documents: registrations:
|id| |id|document_id|date|
My simplified query:
SELECT *
FROM (SELECT documents.*,
(SELECT max(date)
...
0
votes
0answers
39 views
Order By not working correctly in common table expression in Fetch clause while retrieving data
I have been working on a stored procedure optimization which fetches data from multiple tables with many left joins.
The problem I am facing is that in common table expression while fetching the ...
3
votes
0answers
40 views
MySQL uses INDEX for optimizing ORDER BY with GROUP BY except when you add a JOIN
Question
Why can't Query #2 use the same (car_trims.horsepower_peak) index to optimize the sorting of the rows as Query #1? The only difference between the two queries is the addition of the JOIN in ...
1
vote
1answer
55 views
MYSQL - How to optimize VIEW performance?
Total profiles - 100000
Each profile is connected to one or more platform
Each profile have 50 Tags
Each profile have 4 themes
I have a user view (total users around 100000) where I am joining all ...
0
votes
0answers
12 views
I'm trying to order a table with 3 columns as if the columns were merged into 1 such that it would sort as 3 separate entries
I've hit a somewhat unique obstacle with my current project. Below is a mock MySQL table to better describe the issue I'm trying to solve.
mysql> describe `minimized_event_instructions`;
+---------...
1
vote
2answers
42 views
MYSQL: How to optimize a date sorted table with a triple primary key index
I have been maintaining a MYSQL database for a few years, dating from back when i took database managing classes. Its biggest table has since grown (15 million entries for 1,8 GB) and this query began ...
2
votes
2answers
71 views
Select random database records between subset of records having the same count(*) in a query
I have this simple query:
SELECT `value`, count(*) as `noHits`
FROM `topic`
WHERE identifier IN ('" . implode("','", array_keys($processedIdentifier)) ."')
GROUP BY `value`
...
0
votes
1answer
60 views
Order By First Condtition and If multiple matches, order by second condition
I was practicing SQL problems at hackerrank.com when I came across the following question:
Query the Name of any student in STUDENTS who scored higher than
75. The Marks field in the table stores ...
0
votes
2answers
32 views
Order by is ignored if inside a derived table of a update (only in MYSQL 5.7)
I have a update to fix positions values inside a table. The update worked fine in MYSQL 5.5, but after upgrade to MYSQL 5.7 it doesnt work anymore. Now, the "order by" inside the derived table is ...
2
votes
1answer
50 views
PostgreSQL ORDER BY clause effect different number of rows to return in pivot table
I've worked on "Seven Databases in Seven Weeks" recently, and when implementing the the task with building a pivot table using crosstab() - the task was already described here: https://stackoverflow....
0
votes
0answers
25 views
Postresql using subquery select in order by clause
Is it possible to order by a selected columnname?
SELECT * FROM tablex ORDER BY quote_ident((
select column_name from information_schema.columns
where table_name = tablex AND column_name LIKE '...
0
votes
1answer
54 views
Can queries that users ORDER BY using date to sort data be non deterministic?
I have a table in my database where I store dates using the following standard: YYYY-MM-DD. As you can see, I'm not saving the hour. The first time I exported the same table to a csv file I got the ...
0
votes
1answer
78 views
Efficient partition pruning with ORDER BY on same column as PARTITION BY RANGE + LIMIT?
I've set up a table in MariaDB (10.4.5, currently RC) with InnoDB using partitioning by a column of which its value is incrementing-only and new data is always inserted at the end. For this case, ...
0
votes
1answer
26 views
Force index using the unused index columns having effect as order by for the result set?
if I have a index for (col1, col2, col3, col4), my query put col1 and col2 in the query where clause and force MySQL to use the above index. Would my query result be sorted by col3 and col4 ...
1
vote
1answer
26 views
How to order by then start at first non null value and select a limit for number of values
I have an environmental logger and I am trying to select every 5th row starting at where outsidetemp is not null (I want to include the null values after the first not null value). Is there a way to ...
1
vote
1answer
340 views
Optimize MySQL query and index for multiple column range query
I have a table like this:
CREATE TABLE IF NOT EXISTS `jobs` (
`job_id` varchar(36) NOT NULL,
`job_status` varchar(30) NOT NULL,
`created_at` datetime NOT NULL,
`lease_date` datetime,
...
4
votes
6answers
2k views
Only first column in ORDER BY clause is sorted [closed]
It seems like I've misunderstood the concept of 'Order by'.
I have a table with this structure and data:
CREATE TABLE TestTest (Value1 Int, Value2 Int);
INSERT INTO TestTest VALUES
(1, 10),
(2, 9),
...
1
vote
1answer
202 views
first and last record in one query
i want to select first and last score from such data
WITH t AS (
SELECT 1 user_id, '2019-05-15'::date AS created_at, 4 as score
UNION ALL
SELECT 1 user_id, '2019-05-13'::date AS created_at, 12 as ...
2
votes
2answers
127 views
SQL Preserve the Order in group by
I have records like below in my table.
I want distinct records and when I do group by it loses the Order. I want to maintain the order. I have written below query to get the desired however its not ...
1
vote
0answers
27 views
PostgreSQL - SELECT query with ORDER BY and LIMIT 4 very slow, same query much faster with LIMIT >= 40
I've got following sample query from our Postgres DB:
SELECT * FROM advertised_car a0_
LEFT JOIN car_check c1_ ON a0_.car_check_id = c1_.id
WHERE c1_.status = 'ACCEPTED'
ORDER BY a0_.id
LIMIT 4;
...
0
votes
0answers
62 views
postgres: join tables, order by GREATEST
Having the following table structure
table1
id: BIGSERIAL
updated_at: TIMESTAMP WITHOUT TIME ZONE DEFAULT now()
...
CREATE INDEX table1_updated_at ON table2(updated_at);
table2
table1_id: ...
1
vote
1answer
82 views
Redundant fields in ORDER BY for efficient sorting?
Suppose I have a table SortTest with fields Data1, Data2, Sort1, and Sort2, Key1 and Key2 need to perform the following query:
SELECT TOP 1
Data1,
Data2
FROM SortTest
WHERE Key1 = @key1 AND
...
3
votes
5answers
440 views
Order table by two columns
I would like to order this table but I can not find a way to make it work. Can you help me?
I have this table:
I need this:
I have a table where documents are listed, the first field is the id of ...
0
votes
1answer
40 views
Mysql Performance Issue with Group By/Order By
I am using Mysql 5.7 I have table which having 7006500 rows. My query performing group by and fetching row which has maximum count with each group on column which is already indexed but still takes ...
2
votes
2answers
446 views
First order by importance then group by section
In this table scheme http://sqlfiddle.com/#!9/101a9c/9/0
id section rev importance
2 1 b 6
1 1 a 5
3 2 c 9
5 3 e 6
4 ...
2
votes
3answers
74 views
Identify proper index for group and order by date and hour (2 columns)
PostgreSQL 10.4
I have a table that has already an index on date column. Current query plan is doing a Bitmap Heap Scan using the existing date index. I would like to add a new index for this query, ...
0
votes
2answers
60 views
Poor performance on a 'leaderboard' query
Consider the following 2 tables:
players: | rooms:
id | id
name | type
room_id | embed_code_id
points |
My query needs to fetch the 100 players with the most points from a given ...
0
votes
1answer
436 views
postgresql - trouble to order a list obtained by string_agg
I obtained a list of numbers (and text) by a string_agg.
For instance, that :
"09,12,20,200,217,400,500,90,91,92,Exp3"
This is the string_agg:
string_agg(DISTINCT t_ligne.ligne_code::text, ','::...
3
votes
1answer
165 views
Adding an additional “order by” column gives me a much worse plan
in other words, how can I get rid of the sort operator on the picture below?
the picture above shows the execution plan of the following 2 selects together:
SELECT TOP 1 so.OrgType,...
2
votes
1answer
198 views
Conditional ORDER BY based on NULL values in the column
I have a table like this.
table(student_name nvarchar(20) not NULL, grades int).
When I write
select * from table
order by grades asc
It shows this
student_name | grades
---------------------
...
0
votes
2answers
35 views
How to get the best time from submited values?
I have a MySQL table, and i'm trying to figure how can i get the first result for each user.
For example:
Email Time DateSubmission
usera@email.com | 0:14 | 28/2/2019 00:10
usera@...
1
vote
2answers
386 views
How to cast (a) a date value recorded as a VARCHAR to (b) a specific DATE format for (c) use in an ORDER BY clause
How would I cast a column value (a "non-MySQL" DATE string retained as a VARCHAR) to a "MySQL date" so it can be used for sorting?
I have dates in the format of 06-02-2019 (6 feb) but MySQL itself ...
0
votes
1answer
631 views
Is possible to use ORDER BY with IF ELSE condition?
Here I have some data. I want to show the records which have fav=1 at fast, then I want to show the data where the date is greater than the current date in ascending order(date) and at last the ...
1
vote
1answer
42 views
Sort output of plpgsql function
I'm creating a function in Postgres 9.6 that compares two schemas with the same tables. I want to find tables which are empty in one schema but populated in the other. I'm avoiding the reltuples ...
0
votes
2answers
32 views
How to SELECT most common (viral) from a table and LIMIT results for pagination?
Sorry if it's a dubplicate but I can't find an answer to the question.
Hello there so I have three tables users and articles and likes, a user can write an article, in the table articles there is ...
0
votes
0answers
39 views
Pagination using seek-method with nullable columns, sharing a composite index with ORDER BY
I have the following table:
CREATE TABLE users(
id text PRIMARY KEY, -- actually a uuid
organization_id text NOT NULL,
lname text NOT NULL,
fname text NOT NULL
-- other irrelevant fields
);
...
0
votes
1answer
62 views
Using WITH in sql query
I am trying to replace # with numbers, but the order by is being ignored, and I was told to move the subquery usingWITH or adding a limit to the order by, I tried the latter but it didn't work, and I ...
0
votes
3answers
53 views
What order does Oracle's EXIST condition compare the sub-query results?
I know EXIST works better than IN for larger sub-queries because it checks each sub-query record individually and stops once a comparison is found.
Let's say I can order the sub-query in a way to ...
2
votes
0answers
88 views
Postgres / slow query / order by
I'm joining two tables, filter out results by second table and order results by first table's ID.
The query is super-slow on Postgres Database. I see the issue is in the ORDER BY statement. But ...
2
votes
1answer
54 views
How can I get the last items by date desc then by id desc?
I have a employee course table which holds the current record for each of my employees who have some courses that they have taken. Then I have a history that keeps a static version of the save data ...
21
votes
6answers
2k views
How to prove the lack of implicit order in a database?
Recently I was explaining to colleagues the importance of having a column by which to sort data in a database table if it is necessary to do so, for example for chronologically-ordered data. This ...
0
votes
1answer
611 views
Using MATCH, AGAINST multiple times in MySQL fulltext search
I'm using MySQL database for my e-commerce project.
And here is my query for search:
SELECT DISTINCT p.id, p.name, p.price, p.created_at,
MATCH(p.name) AGAINST('Sony* xperia* FHD* ' IN BOOLEAN ...
4
votes
1answer
61 views
Postgres not smart enough to combine fields in WHERE and ORDER BY for index scan?
I have the following table in Postgres 9.6:
Table "public.TagNotifications"
Column | Type | Modifiers ...
3
votes
1answer
410 views
SELECT Parent-Child with SORT
I have a simple, one level parent child relation table, with following columns:
ID_Asset| Parent_ID_Asset | ProductTitle
I need output grouped by Parent followed by children, and also sorted by ...
