I have two Room Entities like this ones: …and a junction table for Many To Many relationship like this one: …and some composite class for obtaining some kind of “composite POJO”: …then, I have this kind of “composite DAO”: The point of the question is… The one that works returns the list as expected: with each TeacherWithCourses having the Teacher
Tag: many-to-many
Junction table indexing in many-to-many relationship
Let’s say we have a PRODUCT table, ORDER table and a junction table PRODUCT_ORDER. I create a junction table with the following script: Also an index for the PK was created automatically: It is expected that there will be practically only read operations for these tables and I would like to index the junction table intelligently. Usually, I additionally create
How to perform Many to Many Relationship Filter Query
I want to perform a query in MySQL based on a filter. First of all, the two tables that will be used in the query are the following: Equipment: Field Type Id PK, Integer Name Varchar(50) Recipe: Field Type Id PK, Integer Name Varchar(50) The relationship between the two tables is Many-to-Many, so there is a pivot table. The filter
SQL Finding all elements which does not belong to a particular set, in many to many relation
I have problem with this task: Given are the relations Students: ST (S#, SNAME) Lecture: L (L#, LNAME, ECTS) Who attends what: LS (L#, S#) Find students (S# and SNAME) who do not attend any lecture having more than 4 ECTS I know that I can do it by checking whether the MAX value of ECTS for given student is
How to query many-to-many relation with features table (AND condition)
I guess this is a common setting, but as I don’t do that much SQL work, I can’t get my head around this one… So, I’ve got a bunch of songs that have certain features (style of music, mood etc.) and …
EntityColumnNotFound: No entity column “authors” was found. many to many relations on TypeORM and NestJS
I am trying to get the books per user from the get request I have the following problem, it turns out that I am doing a many-to-many relationship but it indicates that the authors entity was not found,…
PostgreSQL / express rookie – create new table or just a new column in existing table? [closed]
Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 2 years ago. Improve this question This will probably get closed for being opinion based but hopefully I can get a comment or two. I’m building a social media app (Express/Postgres/React)
SQL Select to display one to one, one to many from many to many relation
I’m trying to figure out SQL query that will list only one to one relation from below table. Below Table contain 10 record where 8 are many to many relation data and 2 are one to one relation. Request your help with SQL that I can use to query below table and list out 2 records that has one to
SQL many joins many to many
I have 5 tables: Table Reports Many to many table ReportsIpRel Table of InfoProviders Many to many table QueriesIpRel And table of Queries The SELECT I am trying to achieve is the following: I tried many left/inner joins like this: but all for nothing. I have to use where condition: WHERE report_Id = ‘2’ /EXAMPLE I’m trying to do this
Is there any pros to not using Many-to-Many relationship [closed]
Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 1 year ago. Improve this question I have been asked to create a small program for assignment based on given instructions. I was given two tables I