What Is a Foreign Key in FileMaker Pro?

Relational databases structure and maintain associations to related data.

The FileMaker Pro application creates and manages data in a relational database. FileMaker Pro uses primary and foreign keys to create unique records and form relationships to records found in more than one table.

A Database Example

Primary and foreign keys work together to make relationships between tables

Imagine students registering at a college. One student, Jan A., is assigned student ID 300. Each time Jan A. registers for a class, student ID number 300 is associated with the course number in the class assignments list.

The Primary Key

Each record, or row of information in a table, has to be unique in a relational database, which is accomplished by assigning it a primary key, such as a number. In this example, Jan's student ID number of 300 is the primary key for the record of her name.

The Foreign Key

When Jan's student ID number appears in the class assignments table associated with a course number, it becomes a foreign key. A foreign key is a primary key found in another table. Primary and foreign keys work together to allow structured relationships among a record found in many tables.

References

• "Special Edition: Using FileMaker 9"; Jesse Feiler; 2008
• FileMaker Knowledge Base; "External SQL Sources and Key Fields with FileMaker Pro";

Resources

• FileMaker Knowledge Base; "External SQL Sources and Key Fields with FileMaker Pro";