One or Two Primary Keys in Many-to-Many Table?

I have the following tables in my database that have a many-to-many relationship, which is expressed by a connecting table that has foreign keys to the primary keys of each of the main...

What's the difference between identifying and non-identifying relationships?

I haven't been able to fully grasp the differences. Can you describe both concepts and use real world examples?

Still Confused About Identifying vs. Non-Identifying Relationships

So, I've been reading up on identifying vs. non-identifying relationships in my database design, and a number of the answers on SO seem contradicting to me. Here are the two questions I am...

Hibernate : Foreign key has the wrong number of column. should be 0

I am trying to evaluate a mapping in this Hibernate document : section 2.2.3.1. Generating the identifier...

Hibernate: Where do insertable = false, updatable = false belong in composite primary key constellations involving foreign keys?

When implementing composite primary keys in Hibernate or other ORMs there are up to three places where to put the insertable = false, updatable = false in composite primary key constellations that...

An error occurred while saving entities that do not expose foreign key properties for their relationships

I have a simply code in Entity Framework 4.1 code first: PasmISOContext db = new PasmISOContext(); var user = new User(); user.CreationDate = DateTime.Now; user.LastActivityDate =...

Identifying the dependency relationship for python packages installed with pip

When I do a pip freeze I see large number of Python packages that I didn't explicitly install, e.g. $ pip...

Arrays vs Vectors: Introductory Similarities and Differences

What are the differences between an array and a vector in C++? An example of the differences might be included libraries, symbolism, abilities, etc. Array Arrays contain a specific number of...

How to identify a strong vs weak relationship on ERD?

A dashed line means that the relationship is strong, whereas a solid line means that the relationship is weak. On the following diagram how do we decide that the relationship between the Room and...

org.hibernate.AssertionFailure: null identifier in Hibernate @OneToMany relationship

I've a bidirectional @OneToMany / @ManyToOne relationship in the below entities: @Entity public class Item implements java.io.Serializable { // other columns including...

Debugging error message: "A script on this page is causing Internet Explorer to run slowly"

One of my users is intermittently getting a dialog in IE 8 that says: A script on this page is causing Internet Explorer to run slowly This problem has been reported numerous times in the MSDN...

How do you determine functional dependencies and a primary key?

In my Oracle Database Programming course, the first part of our final lab assessment requires that we: Identify the Primary Key of the table as it is currently shown Find all functional...

Enhanced Entity-Relationship Modeling

i have to draw Enhanced Entity-Relationship Modeling from this case : The Georgia Tech Library (GTL) has approximately 16,000 members, 100,000 titles, and 250,000 volumes (an average of 2.5 copies...

Reducing garbage-collection pause time in a Haskell program

We are developing a program which receives and forwards "messages", while keeping a temporary history of those messages, so that it can tell you the message history if requested. Messages are...

Multi-tree and Priority Ordering Algorithm

I would like advice on an algorithm for ordering data. Problem I need to sort a list of records (POJOs) based on several criteria. Parent child relationship (no inheritance, just properties) A...

Cybersecurity (Internet topology classification)

I am trying to draw some insights on a set of Autonomous System (AS) relationships given to me. Data looks like this - as1 as2 relationship 4 567 0 14 6079 0 18 276 ...

Inconsistent behaviour with tm_map transformation functions when using multiple cores

Another potential title for this post could be "When parallel processing in R, does the ratio between the number of cores, loop chunk size, and object size matter?" I have a corpus I am running...

Laravel belongsToMany relationship with only one result

I have a relationship between two tables with a join table that only has one result. When I define a Laravel belongsToMany relationship, instead of returning a collection with only one element I...

Excel - Data Model - Relationship between Tables Not Working

I've tried to find a solution to this problem on the web, however I can't seem to find it. It may be because I'm not searching by the correct phrasing, because it's also hard to describe....

How can I retrieve a user from a password reset token in ASP.NET Core?

I have an ASP.NET Core 2.1 web application and am adding forgot password functionality. I have looked at several examples, and they seem to take one of two approaches. The first approach is to...

How to replicate bracket orders functionality using Interactive Brokers (IB) API (ib_insync) for Python

I have been struggling with getting the bracket order to behave where I can pass an auto expire parameter (goodTillDate) for only the parent. When passing it in the bracket order code, it adds it...

Updating related entity in EF Core

I am using Entity Framework Core with a code-first approach. I hit this error when saving the changes to an entity which has a change to one of its related objects: "The property 'BirdId' on...

How to design the relational database for inventory asset tracking of serialized and bulk items

Background Information: I'm learning Laravel 7 by creating an inventory tracking application. I have two models: Product and Stock. The Product can be Serialized, Bulk, or None...

OverflowError: int too big to convert when formatting date on pandas series plot

I'm trying to plot a pandas series, but I'm encountering an error when I attempt to format the x-axis date. (A related issue was identified in the comments, but it appears that it was resolved in...

Interpreting spatial relationships between points with different marks (multitype point pattern) - using spatstat - and better visualize the results

Let me start off by mentioning that I have no training in statistics and I am new in this field for both spatial statistics and coding in R. However, I am trying to learn how to identify and...

IAM policy/role setup for Start and Stop EC2 instances in a different AWS account

I would like to start and stop EC2 instances in an AWS account (Account: AAA) from another AWS account (Account: BBB). Specifically, I am setting up an API to do this on ECS in Account BBB. When I...

Using two tables as input for multi-output regression with keras, the missing matrix product

In the keras MWE below I'm trying to train a multi-output regression model with 1000 samples having 20 features (X) as input and producing outputs of size 50 (Y). However, I'm missing a step that...

Relationship between PlatformTarget and RuntimeIdentifier in .NET 5

I'm confused about the relationship between RuntimeIdentifier and PlatformTarget in .NET 5. My .NET 5 C# project runs and publishes fine, but PlatformTarget is 'AnyCPU' and RuntimeIdentifier is...

Sqlalchemy: Resolve cartesian product warning for many-to-many relationship with custom primaryjoin

Let's say I have the following database schema: class A(Base): __tablename__ = "a_table" id = Column(Integer, primary_key=True, autoincrement=True) version = Column(Integer,...

Can Python pyreverse generate UML diagram for functions?

pyreverse is a great tool to generate UML diagram from Python codes. However, I found it cannot identify all the classes that has been used within a function. I take the following example to...