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Questions tagged [many-to-many]

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15 votes
3 answers

Modeling a scenario in which each Music Artist is either a Group or a Solo Performer

I have to design an entity-relationship diagram (ERD) for a business context that involves the delineation of music artists, as I will detail below. Scenario description An Artist has a Name, and ...
Boshir's user avatar
  • 151
16 votes
1 answer

Designing a database for a video game business domain with multiple many-to-many relationships

I am relatively new to database design, and I decided to make my own hypothetical database for practice. However, I am having trouble modeling and normalizing it, as I esteem that there are numerous ...
dpolaristar's user avatar
4 votes
1 answer

How to make unique check without creating heavy index in postgres

I need to implement unique check for INSERT and UPDATE operations, but I would prefer to avoid creating heavy unique index (which is approx 12Gb now) on my table. Now I have unique partial index and ...
ramusus's user avatar
  • 143
2 votes
2 answers

How to prevent deadlocks in many-to-many insert/update trigger function?

I'm having a problem with deadlocks on a many-to-many insert and am pretty far out of my league at this point. I have a tweet table that receives thousands of records per second. One of the columns ...
GollyJer's user avatar
  • 381
11 votes
5 answers

Build JSON object from one-to-many relationship data in a single query?

I have a PostgreSQL 9.5.3 DB with tables like this: container id: uuid (pk) ... other data thing id: uuid (pk) ... other data container_thing container_id: uuid (fk) ...
antsyawn's user avatar
  • 255
9 votes
5 answers

Mutually exclusive many-to-many relationships

I have a table containers that can have a many-to-many relationships to several tables, let's say those are plants, animals and bacteria. Each container can contain an arbitrary number of plants, ...
Mad Scientist's user avatar
7 votes
3 answers

SQL - Many-to-Many relationship with same table and with relationship constraint

I have a SellerProduct table. Each row within the table represents product information as offered by a seller. The SellerProduct table has the following columns: id (serial, pk) productName (nvarchar(...
user4321's user avatar
  • 215
3 votes
1 answer

How to model a three-way association that involves Product, Category and Label?

I have the following three tables: products: product_id, product_name, ... categories: category_id, category_name, category_parent_id, category_priority (for sort ordering)...
yemet's user avatar
  • 333
2 votes
1 answer

Efficiently return two aggregated arrays from a m:n table

I have a table for a many-to-many relationship over a users table to represent a follow relationship between users: CREATE TABLE users ( id text PRIMARY KEY, username text NOT NULL ); CREATE ...
Russell Ormes's user avatar
2 votes
1 answer

Creating a database for a scenario involving students, teachers and courses

I am undertaking a project that involves a student management system, but I am struggling to normalise/create relationships between certain tables. Here is my current setup: Models Users(id, first ...
buzzysin's user avatar
  • 121
1 vote
1 answer

UPDATE n:m relation in view as array (operations)

Environment I came up with a view and trigger based solution to modify rows in multiple underlying tables in a Postgres 9.5.3 database. This works reasonable using Qt's model view programming. The ...
maxik's user avatar
  • 255
0 votes
1 answer

Why do these queries deadlock and how to work this around in MariaDB?

The following 2 queries enounter DB deadlock in my program: DELETE FROM proxies WHERE NOT EXISTS ( SELECT 1 FROM proxy_xref_proxy_list AS pxpl WHERE pxpl.ProxyID=proxies.ID AND (pxpl....
Serge Rogatch's user avatar