# foreign key

CEFR C1 · Compound

Source: https://englishreference.com/word/foreign-key
Updated: 2026-07-22

## Definition

a field in a database table that connects to a different table. You use it to link information together, like connecting a customer's ID to their specific orders.

For teachers: a column or group of columns in a relational database table that provides a link between data in two tables. It acts as a cross-reference by pointing to the primary key of another table, thereby maintaining referential integrity.

## Examples

- The customer ID is a foreign key in the orders table.
- When designing the database, we used a foreign key to ensure that every order is linked to a valid product ID.
- Enforcing referential integrity through a foreign key prevents the database from containing orphaned records, as the system will reject any entry that does not have a corresponding primary key in the parent table.

## Usage notes

- Commonly used in the context of relational database management systems (RDBMS).

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.