Many to Many Relationship - Displaying rows in multiple tables
First question here.
So a bit of background, I'm pretty new in the development field and am creating a Database-first MVC app that basically functions as a log of video games and their genres for gamers to discover new and old games based on the genres that peak their interest. This necessitates a many-to-many relationship given one game may be classified under several genres and one genre can have multiple games classified under it. As it currently stands in my SQL Database, I have three tables - Game, Genre, and a linking table. The linking table has a FK for both the GameID as well as the GenreID. To my understanding (or lack thereof) since there's a linking table and no actual FK for genre in the Game table itself, how would I be able display the multiple genres applied to each game on each individual game's info page? Is there something I'm missing that I could include in one of the tables, a possible SQL query that would help, or is there some kind of hard coding I can do in Visual Studio once I import my DB in to program the rest of the app?
My database looks like:
CREATE TABLE Game ( GameID INT IDENTITY(1, 1) NOT NULL, Name NVARCHAR(50) NOT NULL, GameDescription NVARCHAR(200) NULL ) CREATE TABLE Genre ( GenreID INT IDENTITY(1, 1) NOT NULL, Genre NVARCHAR(20) NOT NULL ) CREATE TABLE GameGenre ( GameGenreID INT IDENTITY(1, 1) NOT NULL, FOREIGN KEY ('GameID') REFERENCES Cities('GameID'), FOREIGN KEY ('GenreID') REFERENCES Cities('GenreID') )
Thank you in advance. Any and all advice is greatly appreciated!
Splitting data into related tables (article), How do you join two tables with many to many relationships? The table rows reveal a granularity of year and product category. In other words, targets—used to measure sales performance—are set each year for each product category. Because the Target table stores data at a higher level than the dimension-type tables, a one-to-many relationship cannot be created. Well, it's true for just one of the
Just "join" all of your 3 tables. Reference can be found here
How to Handle a Many-to-Many Relationship in Database Design , Why do we need an associative table for many to many relationships? Most forms that represent records from tables that have a many-to-many relationship treat the many-to-many relationship as if it were a one-to-many relationship: The form displays only a single record from one side of the relationship and all—and only—the related records from the other side (usually with a subform or a list control).
Can you try below, and let me know if you have any questions
SELECT G.GameID, G.Name, G.GameDescription, Genre.Genre FROM Game G LEFT JOIN GameGenre GG ON G.GameID = GG.GameID LEFT JOIN Genre Genre ON GG.GenreID = Genre.GenreID -- WHERE if you have any where statement
Many-to-many relationships. A many-to-many relationship occurs when multiple records in a table are associated with multiple records in another table. For example, a many-to-many relationship exists between customers and products: customers can purchase various products, and products can be purchased by many customers. A one-to-many relationship is the most common kind of relationship. In this kind of relationship, a row in table A can have many matching rows in table B. But a row in table B can have only one matching row in table A. For example, the "Publishers" and "Titles" tables have a one-to-many relationship.
This article defines the different types of relationships between lists of entities and provides Many-to-many relationships and junction tables record, and every record in the museums table is linked to one or more records in the works table. Relationships connect two or more tables of data together. To connect each table, both tables must have something in common. There are two types of relationship, a one to many which work very well in Power Pivot and DAX. Then there are Many to Many relationships, which can cause problems. I have even heard people say, Power Pivot does not
Many-to-Many relationships occur when two tables are joined on a field You can now use this Guest ID field as the rows or axes elements of a widget, pulling in of tables T1, T2 and T3, we'd like to run a query that will display aggregations As with one-to-one relationships and one-to-many relationships, there are times when it makes sense to represent many-to-many relationships on a single, self-linking table, such as when all entities are of the same class. Suppose you wanted to track the friendships within a group of people.
Two one-to-many relationships are added to relate the tables. It's not possible to display table rows in the Power BI Desktop model diagram. Many-to-many relationships. A many-to-many relationship occurs when multiple records in a table are associated with multiple records in another table. For example, a many-to-many relationship exists between customers and products: customers can purchase various products, and products can be purchased by many customers.