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Databases & SQL vocabulary · Data Modeling and Normalization

Many-to-many relationship

Meaning in databases & SQL, with examples

nounCommon term

In databases & SQL, many-to-many relationship means: A link where many rows in one table can relate to many rows in another, like students and courses. It needs a third table in between to store the pairs.

In Turkish: çoka-çok ilişki, çok-çok ilişkisi

How it is used

The table in the middle has many names: junction table, join table, bridge table, link table or associative table. It usually holds two foreign keys that together form its primary key, and sometimes extra data such as the date a student enrolled.

Example sentences

  1. Products and tags have a many-to-many relationship, so we added a product_tags table.

  2. In an interview, explain how you would store a many-to-many relationship between users and roles.

Common collocations

  • many-to-many relationship
  • junction table
  • bridge table
  • N:M relationship
  • one-to-many relationshipA link between two tables where one row in the first table can be connected to many rows in the second, but each of those belongs to only one, like a customer and their orders.
  • composite keyA key made of two or more columns that identify a row only when used together, such as order ID plus product ID in an order items table.
  • foreign keyA column in one table that points to the primary key of another table, linking the two and stopping you from storing references to rows that do not exist.
  • ER diagramA drawing of a database design that shows the entities (usually tables), their attributes and the relationships between them, such as one-to-many.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Data Modeling and Normalization

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