Questions tagged [join]
An SQL join clause combines records from two or more tables or views.
1,986
questions
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72
views
How to allow predicate pushing on a view that uses group by
We have a table Ecom.McProductToVendorProductCodeMap that has a multi-field PK as shown:
Then a view wraps that table to compute a metric and is grouped by the first two fields of that PK:
ALTER view ...
- 2,078
0
votes
2
answers
55
views
Duplication records with INNER JOIN
I’m validating records after a partition’s rotation.When I run the SELECT COUNT for each table I get 114,817,959 records.
SELECT COUNT(*) FROM SMS.dbo.MessagesPerf WITH (NOLOCK) WHERE
DateEntered &...
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-1
votes
1
answer
54
views
Question on joins with multi tables
I have 4 tables ( 1 to many table relation) as shown
Main , Worker , Location and MiddleName Table
Any suggestions on how to get the result. I tried joins and it never worked.
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0
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1
answer
25
views
SQL Pattern to get "root/ start" of uneven hierarchy dataset
I feel this is a common problem and I've seen it in some SQL challenges even but for the life of me, cannot think clearly about a solution.
Say you have an uneven hierarchy. Elements that belong to ...
- 1,651
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votes
1
answer
26
views
UPDATE table vs JOIN performance
I currently have a query with roughly 10 JOIN statements that takes about 10 seconds to run. I have this displayed as a report on SSRS.
Would it be better to create a table in SQL server and run ...
- 121
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0
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42
views
Complex day-to-day difference of historical data in SQL server
Setting:
I have a table (let's call it "HistoricalData") with 10 attribute columns, a date (in string format) and a value. The table has a unique clustered index on (date, idcol1, idcol2,.....
0
votes
2
answers
102
views
How to apply JOIN only if there are rows available
Given the following database:
CREATE TABLE "Activity"
(
"id" INTEGER PRIMARY KEY NOT NULL GENERATED ALWAYS AS IDENTITY,
"designation" TEXT NOT NULL
);
CREATE ...
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1
vote
1
answer
70
views
Does SQL implementations (or at least SQL Azure) skip obvious duplicate data with joins when returning data?
Say I have:
very wide table A where I need all columns
that I need to join with a small table B that has a LOT of rows.
Of course when I join these two tables I get returned all the content of A for ...
- 355
1
vote
1
answer
75
views
Limit results of complex query to most frequent values in given attribute
Say that you have the following tables for a multi store platform
CREATE TABLE orders (
id BIGINT PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
store_id BIGINT NOT NULL,
ordered_at TIMESTAMPTZ NOT ...
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0
votes
1
answer
20
views
I am getting an infinite fetch duration when adding a similar third left join
I am using MySQL on Windows 10.
The query below should result in three groups of data sets that are different only in the date range. It works for any two date ranges but when I try to run all three ...
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0
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22
views
SELECT for VIEW with steped date dependencies
I have two tables on a mariadb 13.0 - values:
id
date
value1
value2
1
2023-10-01
10
100
2
2023-10-02
20
200
3
2023-10-03
30
300
4
2023-10-04
40
400
5
2023-10-05
50
500
and rates:
date
rate1
...
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0
votes
0
answers
5
views
Handling clunky join condition (Newbi)
(Newbie question I think) [Not a mission critical issue just for my understanding].
I have a situation where I have two SharePoint tables as follows:
Table 1: UserTable: user, Position, Department, ...
1
vote
0
answers
53
views
Adjust SQL query to select only one record
I have three tables:
An adjacency-list table, territories with fields id, alignment_id, three_left, tree_right, depth and deleted_at (omitted from table for brevity, all values null).
id
alignent_id
...
- 61
0
votes
2
answers
98
views
Does the JOIN really duplicate data on the level of response from the database?
As an example, let's take PostgreSQL and say we have two tables with one to many relationship. Making the INNER JOIN produces "duplicates" from the first table. Are those duplicated rows ...
- 3
1
vote
1
answer
43
views
How can I SELECT columns from one table that corresponds with a column of another table on JOIN without creating a relation between the tables?
I have 3 tables:
CREATE TABLE catalog.shoes (
shoe_id SERIAL PRIMARY KEY,
brand VARCHAR(255) NOT NULL,
model VARCHAR(255) NOT NULL,
price INT NOT NULL,
CONSTRAINT shoe_name UNIQUE (...
- 121
0
votes
1
answer
29
views
Get Point from Another Table based on Category and Value Range
I am trying to get a column which specify the points by comparing the value from original table to min and max value from another table. I have a main table, which consists of few columns of values ...
0
votes
1
answer
33
views
Why use $group / group_by instead of multiple requests?
Let's suppose that there are 100 types of dogs scattered across the documents of my collection. If I need to group by types of dogs and then compute some aggregate statistic about each type of dog, ...
0
votes
1
answer
30
views
Slow join on geometry fields
My situation is somewhat similar to this earlier question: In PostgreSQL I have one table containing point geometries (P), and another containing polygons (G). I would like to join on the geometry ...
- 121
0
votes
2
answers
114
views
Is it a good idea to join data from two different databases?
I am building an application that requires a lot of tables in one database and while the joining and aggregation of data is really nice and seamless, I am starting to wonder if I am creating too many ...
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0
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1
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66
views
UPDATE & SELECT & INNER JOIN combined (SQL92) — How?
I have two tables with the following columns:
Table1
id
Sort
dou
and
Table2
id_Table1
Sort
and I need to read all values of Table1.Sort where Table1.dou = 1 and write them into Table2.Sort, into ...
0
votes
0
answers
34
views
Dynamically selecting a table in a query based on result from joined SELECT
I have seen many examples but they don't match with my special case (I know... everyone's case is a special case :D )
I have to match values from different tables, some of which are named after the id ...
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2
votes
2
answers
299
views
Ignore duplicate rows in a join - and take only one of them
In MySQL I have tables, simplified as follows:
companies (id, name, rank, trade_sector_id)
orders (id, company_id, paid, subtotal)
trade_sectors (id, label)
companies_notes (id, company_id, notes)
I ...
- 123
0
votes
1
answer
45
views
Join 1 row out of multiple 1:1 tables and return as array of json objects
I have a database structure like so (in Postgres):
An entity has a list of actions associated with it. Each Action has one associated row out of all action-specific tables. Each of these action types ...
- 1
0
votes
1
answer
57
views
Help with SQL Query: Is there a cost-efficient way to join multiple tables to one main table?
I have a main table set up like this:
id
table_to_join
table_item_id
1
products
123
2
products
577
3
products
344
4
products
1230
5
images
14
6
images
42
7
video
555
8
products
400
9
video
9
...
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0
votes
2
answers
51
views
Delete all rows if input parameter is 0 otherwise delete only those entries which match the input param
I have a stored proc which is receiving id as input. If the id which is received is 0 then we need to delete all the rows otherwise we need to delete only those rows which matches the input id.
I can ...
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3
votes
5
answers
1k
views
Optimizing SQL Server Query When Joining Tables on DATETIME column
I am working with SQL Server and I have two tables, table1 and table2. Both tables have a DATETIME column denoted as dt. I need to join these tables based not only on certain conditions but also to ...
- 1,159
2
votes
2
answers
180
views
Column isn't in GROUP BY error on join query
I'm trying to get best selling products.
Tables
CREATE TABLE `items`
(
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) NOT NULL,
`price` ...
-3
votes
1
answer
90
views
subquery vs join which is better [closed]
SELECT *
FROM
table1
WHERE
t2id in
( SELECT id FROM table2
WHERE t3id =
(SELECT id FROM table3 WHERE id = '1') );
SELECT * ...
- 97
1
vote
1
answer
66
views
PostgreSQL: Sum filtered items in a one-to-many relation
I have events and sessions associated with them in a one to many relation. I want to make a query to get the amount of past, happening and upcominng events.
Past events have no active sessions
...
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1
vote
2
answers
59
views
How to optimize SELECT COUNT with LEFT JOIN?
I have a MariaDB 10.5.10 database, with a table activity made of 150,000 rows. it holds:
an id field (integer, primary key)
a tenant. There are about 85,000 rows with tenant = 12
an activity_type (...
- 113
0
votes
1
answer
51
views
How to join matching Date fields as intervals?
Let say I've a table with a list of id/year/month (two years + 24 months for semplicity here):
Code Year Month
MAT000000001 2022 1
MAT000000001 2022 2
MAT000000001 2022 ...
- 243
0
votes
1
answer
29
views
Joining per group in group by
I have a table with some animal sightings data where each sighting entry has a region field. There can be 0 to many entries per region per day.
I need to create a query where there is one row per day (...
0
votes
1
answer
635
views
Left Join with only one of multiple matches in the right table
I have a database, where every entry may have multiple names, therefore I made a name database. While all names will be displayed otherwhere I need a list of all main entries with one representative ...
- 1
0
votes
1
answer
42
views
Different index selection and join strategy between QA and Prod environments in PostgreSQL
I have encountered a scenario where the same query on a PostgreSQL database is exhibiting different index selection and join strategies between the QA and Prod environments. I'm trying to understand ...
- 213
0
votes
1
answer
37
views
Compositing ordered SQL tables without Joins
I'm currently exploring some weird ways of doing things and was wondering if anyone has any experience with the following methodology.
Background
I have a handful of NF3 tables, and NF1 source data. ...
- 117
0
votes
2
answers
26
views
SQL multilevel join how to add a where condition
I have the following SQL query
SELECT
r.id as id,
reports.Timestamp as reportTimestamp,
reports.Latitude as reportLat,
reports.Longitude as reportLng,
FROM Requests r
LEFT ...
- 141
0
votes
0
answers
423
views
MySQL indexes on temp tables
I am trying to perform joins between two temporary tables, creating an index on the join key for each temp table. However, when I EXPLAIN the join, the row estimates always seem to come out vastly ...
- 1
0
votes
1
answer
36
views
Join two tables with similar columns
I hva two tables as is:
Table univers:
client
commercial
Axel
Tony
Mike
Jhon
Chris
Jhon
Table transactions
frclient
toclient
commission
Axel
NA
10
Mike
NA
8
NA
Mike
15
Axel
NA
4
NA
Chris
5
...
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0
votes
0
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23
views
How to Join two tables with SUM in SQL server [duplicate]
i have 2 tables
1.registros
2.servicios
what I wanna have is this: id,nombre,apellido,direccion,telefono servicios_pedidos of table 1 + sum of table 2 servicion.precios with table 1 registros.[...
- 1
1
vote
2
answers
75
views
How to leave only the rows with an timestamp difference with an interval greater than a parameter
I have a Postgres table with timestamps as entries.
From this table, I would like to calculate a new one where there are no consecutive entries with a timestamp difference shorter than 400 ...
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0
votes
1
answer
13
views
Issue in Retrieving data from Table when it is having more than 1 records for 1 ID
I have a table ABC and it has 5 columns and now I need to find such records in the table for same ID value where the value in columns C is 0 in all the cases.
Solution please.
0
votes
4
answers
150
views
LEFT JOIN 3 tables NULL rows not as intended
Scenario - a sailing event with entrant categories.
I am a volunteer and I am struggling to get a result table for each entrant listing their selection (or NULL if none chosen) for each category. ...
- 1
0
votes
1
answer
148
views
Joining Columns with different character set
I am joining two tables on varchar columns having CHARACTER SET utf8 COLLATE utf8_bin and one with CHARACTER SET latin1. Indexing is not working when i am joining these two tables on this column, I am ...
0
votes
1
answer
23
views
update row with age calculation with DOB in related table
SQLite database with a table "events" with a columns events.eventDate, events.ageAtEvent and events.foreignKey_participants, and a table "participants" with columns participants....
0
votes
1
answer
34
views
Select tables data with sum of other tables
I am very new on MySQL DBA and i searched but i am not clearly understanding inner join with sum.
user table:
id, username, locationid
history table:
id, username, locationid, spent
Example user ...
0
votes
1
answer
79
views
SQL Server 2014 Cardinality Estimator estimate final number of rows after OUTER JOIN is less than number of rows from initial table
I have a [SQL query] for SQL Server 2019.
It works fine with option
(USE HINT ('FORCE_LEGACY_CARDINALITY_ESTIMATION'))
and very bad without this hint.
I found out, that SQL Server 2014 Cardinality ...
2
votes
2
answers
92
views
Join order and nullability
I am asking this question in the context of using a Postgres database, although I would imagine it would apply to most SQL databases.
When working with the results of a database query inside a ...
- 243
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votes
1
answer
94
views
ORA-12015 materialized view complex query error with simple join two table
I have 2 simple table which has columns like :
table1 :
"OBJECTID" NUMBER NOT NULL ENABLE
"OLCEK_ID" NUMBER(*,0)
table2 :
"OBJECTID" NUMBER NOT NULL ENABLE
i created ...
1
vote
1
answer
77
views
Worst performance multiple left join big tables after restore DB
Problem
Database: PostgreSQL 13.8 (Debian 13.8-0+deb11u1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
After migrate from DigitalOcean to strong Dedicated Servers ...
1
vote
1
answer
109
views
What's the fastest way to query multiple tables at once where each table represents one year of data?
I'm developing an web app based around a database with multiple decades of data with multiple schema changes over the years. Each year of data is released as a zip file containing CSVs named table1....
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