Relational Database Design for Multiple User Types
When designing a relational database for multiple user types, there are several approaches to consider. One classic method is "Single Table Inheritance," where all user types are stored in a single table with a column indicating the user type. Common data is shared among all rows, while type-specific data is stored in nullable columns.
Another approach is "Class Table Inheritance," which employs a base table for shared data and separate tables for each user type. Each subclass table contains data specific to its type and references the base table via a foreign key.
To avoid multiple queries for user data, you could implement "Shared Primary Key." In this technique, the id column in each subclass table is a copy of the id column in the base table. This ensures a one-to-one relationship and optimizes joins.
Ultimately, the choice of design approach depends on your specific requirements. Single Table Inheritance is a space-efficient option that requires additional conditional logic to handle type-specific data. Class Table Inheritance with Shared Primary Key provides faster queries and enforces data integrity but may introduce more complexity.
Consider the trade-offs and choose the design that best suits your application's performance, flexibility, and ease of maintenance requirements.
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