Questions tagged [order-by]

A clause used in SQL SELECT statements to sort query results.

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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-...
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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....
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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 ...
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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 ...
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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 ...
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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" ...
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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) ...
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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 ...
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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 ...
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1answer
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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 ...
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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`; +---------...
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2answers
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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 ...
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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` ...
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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 ...
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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 ...
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1answer
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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....
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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 '...
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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 ...
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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, ...
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1answer
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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 ...
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1answer
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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 ...
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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, ...
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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), ...
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1answer
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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 ...
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2answers
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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 ...
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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; ...
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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: ...
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1answer
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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 ...
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5answers
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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 ...
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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 ...
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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 ...
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3answers
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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, ...
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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 ...
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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, ','::...
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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,...
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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 --------------------- ...
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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@...
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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 ...
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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 ...
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1answer
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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 ...
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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 ...
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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 ); ...
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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1answer
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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 ...
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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 ...