Stack Overflow
Stack Overflow

Questions tagged [cardinality]

In data modeling, the cardinality of one data table with respect to another data table is a critical aspect of database design. Relationships between data tables define cardinality when explaining how each table links to another. In the relational model, tables can be related as any of: many-to-many, many-to-one (rev. one-to-many), or one-to-one. This is said to be the cardinality of a given table in relation to another.

In data modeling, the cardinality of one data table with respect to another data table is a critical aspect of database design. Relationships between data tables define cardinality when explaining how each table links to another.

In the relational model, tables can be related as any of: many-to-many, many-to-one (rev. one-to-many), or one-to-one. This is said to be the cardinality of a given table in relation to another.

Wikipedia article

274 questions
9
votes
1 answer

What is cardinality and how does it affect performance (SQL Server)?

We have a massive table where I need to make an update on a single row. I don't know the primary key of the row, but I have a varchar value that is unique within that table. I also have the value of a few other columns in that tables. Running the…
Reverend Gonzo
  • 39,701
  • 6
  • 59
  • 77
9
votes
1 answer

How do I add multiplicity values in StarUML

I am studying Database Development and I am at the stage where I have to create my own ER Models. Everything is fine so far with StarUML however the course notes don't mention how to add muliplicity options between entity types (the cardinality and…
Peter Stuart
  • 2,362
  • 7
  • 42
  • 73
8
votes
6 answers

What is the difference between Max Cardinality and Min Cardinality?

I am having a hard time understanding what is the difference between the Max and Min cardinalities when trying to design a database.
Steffan Harris
  • 9,106
  • 30
  • 75
  • 101
6
votes
2 answers

ClickHouse: Does it make sense to use LowCardinality fields on Uint8 used as Boolean?

LowCardinality fields in ClickHouse are an optimization where the values are dictionary-encoded for faster lookups and smaller storage. As per documentation: The efficiency of using LowCarditality data type depends on data diversity. If a…
xmar
  • 1,729
  • 20
  • 48
6
votes
0 answers

Cardinal numbers with NumberFormatter using Locale settings in Swift

How can I generate cardinal numbers(One, Two, Three) using NumberFormatter in Swift using Locale settings. For example, I am able to convert 1 minute -> One minute using English Locale settings. But for Norwegian it should be Et minutt, While it…
Umair Aamir
  • 1,624
  • 16
  • 26
6
votes
3 answers

Java fastest way to get cardinality of BitSet intersection

The function below takes two BitSets, makes a copy of the first (it must not be overridden), intersects the copy with the second (bitwise AND) and returns the cardinality of the result. public int getIntersectionSize(BitSet bits1, BitSet bits2) { …
Brandon McHomery
  • 173
  • 1
  • 10
6
votes
2 answers

How do I best represent a one-to-many relationship where one child is a special case?

I have a schema with a parent-child relationship between two entities. It's a one-to-many, so would naturally be implemented as: table Parents id table Children id parent_id However, I also need to treat one of the children as a special case…
troelskn
  • 115,121
  • 27
  • 131
  • 155
6
votes
2 answers

Entity Framework Cardinality Issue on a 0...1 Association

I have database tables that look like this: A Task can be mapped to a Module, or not mapped at all (0...1). I'm using Entity Framework database-first, and when I generated the model from the database, the Task entity came through with Modules as a…
AJ.
  • 16,368
  • 20
  • 95
  • 150
5
votes
1 answer

SQL: Enforce cardinality with assertions

To explain the diagram. Two entities: E1 & E2 Cardinality: -from E1 to E2 (through relation R): (6,50) -from E2 to E1 (through relation R): (3,5) ______ ^ ______ | E1 |___(6,50)____/R\____(3,5)___| E2 | |______| …
ecr
  • 391
  • 1
  • 3
  • 7
4
votes
2 answers

crazy cardinality counts for show table status

Iteration1: mysql> show table status LIKE…
Stewie
  • 3,103
  • 2
  • 24
  • 22
4
votes
1 answer

With DIA diagramming program, how to add cardinality notations on relationship lines?

I am using DIA v0.97.1 to draw an entity relationship diagram with UML sheet for my database model. However, I tried and failed to find a switch allowing me to add cardinality notations (e.g. 1...n) on those relationship lines. Is there such a…
Frank Huang
  • 55
  • 1
  • 3
4
votes
5 answers

Update statement taking too long to execute

I am running a Simple Update statement. Its taking too long to execute. Here are the Update and index details. The default value of Exported column is 0 UPDATE PAR_ITM SET exported = -1 WHERE exported < 1 Indexes: CREATE NONCLUSTERED INDEX…
Prateek
  • 231
  • 3
  • 6
  • 12
4
votes
2 answers

Confused on the difference between One, and One and Only One in ERDs

Sorry for the links I'm new! I'm confused on the difference between one and one and only one and where they would be used. I just started the class so I apologize if my diagram is wrong as well. Hospital Problem ER Diagram
Carolyn Johnson
  • 41
  • 1
4
votes
1 answer

Cardinality of Prop, Set and Type_i in Coq

Can we assign cardinals in Coq to Prop, Set and each Type_i ? I only see the definition of finite cardinals in Coq's library, so maybe we need that of big cardinals to begin with. According to the proof-irrelevance semantics, for example exposed…
V. Semeria
  • 3,128
  • 1
  • 10
  • 25
4
votes
2 answers

RBAC (Role Based Access Control) ER Diagram

I am trying to design an application with Role Based Access Control. And I have also designed the ER Diagram. So here I try to achieve that a USER will have a single ROLE and based on the particular ROLE it will get permissions for RESOURCES set in…
Himadri Ganguly
  • 715
  • 4
  • 11
  • 31
1
2
3
…
18 19