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Questions tagged [subquery]

SQL term used to describe when a `SELECT` statement is used as part of a larger SQL statement. The larger statement may be DML and is always found within brackets or parenthesis.

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23 views

Run Comparisons between average data and raw data in PostgreSQL

i am having a problem and i am trying to solve but i do not know which approach should i follow. I am having the following structure in my raw data table I am trying to apply some calculations and ...
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13 views

how to optimise update using subquery in PostgreSQL

I have got a table with just above 30million records and I have been running this query but I then realised that it is somehow taking too much time update foo_bar set bd_length =foo.total_length ...
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1answer
31 views

Calculating percentage over sub query SQL

I have a table that records events regarding email campaigns. I want to figure out the percentage of campaigns where there was more than one event happening for the campaign. First I calculated the ...
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1answer
34 views

Query with a few subqueries and appropriate indicies taking, on average, 613ms to execute

I have a ton of queries that do a similar thing as to what I'm doing here, but none of them have the performance issues this one does: SELECT (SELECT lead_id FROM leads WHERE to_id = lead_id OR ...
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1answer
52 views

Aggregate function on subquery

I have got a SALES table that has 4 document types, and they are created with reference to each other in the following order: Offer -> Order -> Delivery -> Invoice. For each new row their ...
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14 views

adding results of InfluxDB subqueries

I'm trying to get the kWh from multiple entities in InfluxDB in Grafana. I have the following raw query. SELECT ("a" + "b") / 3600000 FROM ( SELECT spread("watt_seconds") AS "a" FROM "W" ...
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1answer
451 views

Replace long GROUP BY list with a subquery

This is a repost of my question on Stack Overflow. They suggested to ask it here: I found an online article from 2005, where the author claims, that many devs use GROUP BY wrong, and that you should ...
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1answer
40 views

Sub Query with group by returns more than 1 row Issue

I am facing the issue of subquery returns more than 1 row cause I am using group by in the subquery and outer query both to get the desired result. This is my query SELECT Count(*) ...
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1answer
61 views

optimize query — remove nested selects

How can I rewrite the query to increase performance? Here is the query: SELECT flight.*, DAYOFWEEK(flight.flight_time) AS day_of_week, IF(SUM(...
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1answer
190 views

There is a column named in table but it cannot be referenced from this part of the query

I've been learning Postgres (coming from SQL Server), and this error really confuses me. Here is the code with some sample data: create table T ( ID serial primary key, A varchar(1), B varchar(1), C ...
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1answer
28 views

Need help with correlated subquery

I have two PostgreSQL tables that each contain a column called date_of_incident. They each also have a column called incident_id and this is how the tables are related. I want to update all rows of ...
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2answers
114 views

Can subqueries produce different execution plans than CTE's?

I was talking with the bossman, and he prefers subqueries over CTE's. Personally, I loathe subqueries. He mentioned that subqueries can be faster, but I am not convinced. I ran this short test: ...
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2answers
40 views

Select/print data from subquery

In my application I have a table "user", a table "role", and a table "userroles". Userroles is simple table consisting of user, role, where user corresponds to the id column of the user table. As user ...
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1answer
76 views

Optimize slow COUNT in MySQL subquery

I have the following query that takes minutes to complete: SELECT DISTINCT Designation, Model, ( SELECT COUNT( Equipment.EquipmentID ) FROM Equipment INNER JOIN EquipmentDesignation_Vw ...
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3answers
80 views

Can a `Select` Subquery be conditionally returned? [closed]

Is it possible in Postgres to return a column(Resulting from a subquery) only when a condition matches? Query: SELECT (SELECT NOW()) AS FIRST, (SELECT NOW()) AS SECOND Outputs: | first | ...
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1answer
39 views

Postgres Pass Subquery results to function that returns TABLE

I have a function that accepts arrays as parameters and returns a table. I can get the arguments passed in correctly, but it is returning rows of type record. If I try to expand the record with FROM I ...
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1answer
19 views

Is there a way to alias columns for reference in subqueries?

I have a SQL statement in PostgreSQL that takes the following form: SELECT * FROM db WHERE (b + 1) IN (SELECT b FROM db WHERE a = 7) This query returns each record whose b value, incremented by 1, ...
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1answer
17 views

How to rank an aggregation in each newly formed group?

The problem below that I would like to solve sounds quite simple but it is quite difficult for me to arrive at the solution with SQL. Let's say I have a simplified ERD that looks as follows: This ...
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2answers
35 views

How to get column values in where condition in sub query? [closed]

I am trying to get distinct list of values in where condition through sub query but it shows 0 rows in result set. Here is my query. SELECT a.topic_id, t.id as topicid, t.value as value, t.topic as ...
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1answer
24 views

How to use query result as REPLACE parameters

i'm trying to: 1- Find a string inside a lot of content 2- Replace that specific part of the string with a new one using REPLACE function like this: REPLACE(column_name, query#1, query#2) Is this ...
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0answers
30 views

Two left joins then two on statements [duplicate]

I stumbled upon a left join function that is throwing me off... I was trying to eliminate a subquery or using another temp table. Both of the following queries produce the exact same values. SELECT * ...
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1answer
39 views

Query to get the physical file name of the database

Im trying to get the physical file name of a database, and when i query sys.database_files, under the physical file name column, you get the whole path (ie. S:\Program Files\Microsoft SQL Server\...
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20 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 '...
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84 views

Subquery caching in join

I have very complex MySQL queries that use the same subquery over and over again. I was wondering if MySQL will run the subquery multiple times or use the previous resultset. Is there any way to tell ...
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1answer
38 views

selecting data after filtering out

I am using RDBMS MySQL 5.7. I have 3 tables with the following structures: Table A - primary table - products: +----+-----------+-------------+------------+--------+ | id | title | description |...
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24 views

Finding matching sub values?

So not too sure how to go about this, but ideally I want to pull out matching & non-matching info from an array of rows in a table, so I have a table with info like this: 12,2019-07-15 06:02:52,...
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1answer
38 views

Problem with How to join with subquery

I'm trying to create a report in Postgresql that shows some columns from some tables with join. But one of them is subquery that to show a customer with the location. My Problem is, I always get ...
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1answer
40 views

Why last table don't using index for joining?

By the help of others members i get an Query idea for my previous problem. But after writing this, the EXPLAIN showing that my last table do't using index for join but the joining ROW is PRIMARY KEY, ...
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23 views

How can i remove filesort for this subqueires?

This is the Query: SELECT A.* FROM messages_thread_user mtu, LATERAL (SELECT m.*, u.userName FROM messages m JOIN ...
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0answers
217 views

Sql subquery for nested parent child data

I have two tables , on parent table (categories ) and child table (features).. I have this query select c.* , (select GROUP_CONCAT(f.featuresId , f.featuresTitle ) from ...
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1answer
21 views

MySQL - Optimize subquery in Select, where and order by

Im running a query like below. SELECT DISTINCT c.`id` , c.`job-cat` , ( SELECT COUNT(*) FROM `jobs` j WHERE j.`mul_category` IN (c.`id`) AND j.`ending` >...
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2answers
50 views

Postgres select using lateral

I'm after running a query with a subquery (perhaps inefficient) that using a regular expression pattern it can return how many instances of a characters are included with a given record. In doing so, ...
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1answer
95 views

Query to Find Multiple Start Time and End Time on a Single Day based on Boolean Value

I want to find the multiple Start Time and End time in a single Day based on the Boolean value where data is divided into each half hour interval for a day. So Each day is divided into 24hrs/2 = 48. ...
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1answer
33 views

How do I create a table with count of instances of an id before an event date that is individual to that id?

I am very new to SQL and have a relatively complex query to write, any help would be appreciated. I have data with the following columns: ORDER_ID CUST_ID ORDER_DATE RETURNED(1/0) I need a table ...
0
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1answer
39 views

Slecting specific query returnned data related records from another table [closed]

Product table: productId | productName | unitPrice | supplierId _______________________________________________ 1 | Iphone8 | 1500 | 3 2 | Nokia 6 | 800 | 1 ...
4
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1answer
322 views

How to take make OFFSET & LIMIT with COUNT (OVER?) when having a subquery?

It appears I have a case I can't quite wrap my brains around. So coming here in hopes to find pointers to a query that maybe could be helpful to someone else too. In the following, I have a query ...
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1answer
390 views

Limit left join for multiple rows

Since MySql doesn't support main alias reference in subquery is a bit challenging to create query with multiple rows where you have to limit rows of left join tables. Let's overview simple example. ...
0
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1answer
28 views

Two aggregated sub queries wont run

I am having trouble with the below, I need to average two columns in a correlated subquery and I cannot get it to work, how do i get both aggregate sub queries to run then go through the outer query? ...
2
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2answers
62 views

What am I doing wrong with subquery

I cannot work this out, how do I get the subquery to return the lowest course weight for each lecturer, it currently only returns the lowest and is my subquery wrong or outer query? Question: Show ...
3
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1answer
71 views

Why is an empty rowset not equivalent to null when assigning a query result to a variable and how best to work around?

I have a cursor. Within my loop I select a single column and assign the result to a variable. When the select returns an empty rowset, nothing is assigned to the variable. In particular, the variable ...
0
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1answer
72 views

Cannot get a user function to co-operate with a subquery in mariadb

The following is a demo of an issue we are having with a function and a subquery. I'm interested to know if it is a bug or if there is a reasonable explaination why it is failing. Notes: Problem ...
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1answer
215 views

Having a subquery somehow do the same group by as the outer query

i'm pretty decent with SQL but it's not my main experience of expertise. A colleague asked me a stumper of a question the other day. I was wondering if you guys could provide assistance. Basically we'...
2
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3answers
81 views

Return ALL rows based on a matching date also matching a specific value in another column

I'm using SQL Server 2014, exact version: 12.0.5579.0. I've tried a subquery under a SELECT and WHERE statement and it brings back false results with rows of any row with a 1/1/2019 date. It just ...
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1answer
185 views

When to use lateral joins vs correlated subqueries in Postgres?

These two queries: SELECT username, location, task, ts_next - ts AS diff FROM ( SELECT username, location, task, ts, ( SELECT ts AS ts_next FROM switches ...
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2answers
98 views

MySQL Function work very slow

I have writed this mysql function, it's worked perfekt but very slowly, what can I do for better performance, have you any idea? note:i need all created virtual columns DROP FUNCTION IF EXISTS ...
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1answer
59 views

Print Two Different Columns with Union All- SQL

I have an SQL statement like this, SELECT * FROM (select "John" as FirstName Union All select "Mary" Union All select "Alis"), (select "Doe" as LastName union all select "Queen" union all ...
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1answer
111 views

Why Subquery do not filter the result in multiple Subquery

This is Query (skipped selection for simplicity and also it work perfect): SELECT * FROM (SELECT a.striker FROM ball_by_ball a LEFT JOIN batsman_scored b USING (...
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0answers
42 views

MySQL How to get first row from subquery when using aggregate function

This is my Query: SELECT COUNT(runs_scored) - SUM(IF(extra_type_id = 4, 1, 0)) AS Balls, SUM(runs_scored) + SUM(IF(extra_type_id IN (2 , 4), extra_runs, 0)) AS Runs, SUM(...
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0answers
15 views

How to find full siblings? I have been able to find the parents, but can't figure out how to join siblings based on having same parents

I have two tables (table/column names not my choice): | Person | | Parent | ------------------------------ ----------------------- | ...
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20 views

Combine multiple queries that each require a row of input values

I'm looking for a way to combine multiple queries that each need two values. For example, I can look up a patient's age and weight as follows: select age , weight from patients join ...