Can a Deductions Table Have Foreign Keys Referencing Multiple Primary Keys in Separate Employee Tables?

Foreign Key Constraints Across Multiple Employee Tables

This article explores the possibility of creating foreign key relationships in a deductions table that link to primary keys in multiple employee tables (employees_ce and employees_sn) within a single database.

The challenge arises from having two distinct employee tables, employees_ce and employees_sn, each with its own primary key (empid). The goal is to create a foreign key in the deductions table referencing both primary keys.

An example dataset is presented showing the data structure of employees_ce and employees_sn, and the intended foreign key references in the deductions table.

Optimal Database Design

The most effective solution is to restructure the database using a more normalized approach. Instead of separate tables for ce and sn employees, a single, unified employees table should be created with a unique id field as its primary key.

The existing employees_ce and employees_sn tables can then be refactored as child tables containing employee-specific attributes. Both would include a foreign key referencing the id field in the main employees table.

This consolidated approach eliminates the need for multiple foreign key references in the deductions table, simplifying the database schema and improving data integrity. The resulting structure is more efficient and easier to manage.

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