Database Schema Design

This skill enables an AI agent to design robust, normalized relational database schemas from application requirements. The agent analyzes entities, defines tables with appropriate data types and constraints, establishes relationships (one-to-one, one-to-many, many-to-many), applies normalization up to 3NF, creates indexes for query performance, and produces complete SQL DDL scripts ready for execution.

Workflow

1. Gather and analyze requirements: Interview the user or parse a specification document to identify all entities, their attributes, and the relationships between them. Clarify cardinality (1:1, 1:N, M:N), required vs. optional fields, and any domain-specific constraints such as unique emails, positive prices, or enumerated statuses. Document assumptions explicitly before proceeding.

2. Model entities and relationships: Translate requirements into a logical data model. Define each entity as a table, choose appropriate primary keys (prefer surrogate integer or UUID keys for stability), and map relationships. For one-to-many, add a foreign key on the "many" side. For many-to-many, create a junction table with composite primary keys referencing both parent tables. For one-to-one, use a shared primary key or a unique foreign key.

3. Apply normalization: Review the schema against normal forms. Ensure every non-key column depends on the whole primary key (2NF) and only on the primary key (3NF). Split tables that contain transitive dependencies. Strategically denormalize only when justified by read-heavy query patterns, and document the trade-off.

4. Define constraints and indexes: Add NOT NULL, UNIQUE, CHECK, and DEFAULT constraints to enforce data integrity at the database level. Create indexes on foreign key columns, columns used in WHERE clauses, and columns used for sorting or grouping. Consider composite indexes for multi-column query patterns.

5. Generate SQL DDL scripts: Produce complete CREATE TABLE statements with all columns, types, constraints, and indexes. Use IF NOT EXISTS for idempotency. Order statements so that referenced tables are created before referencing tables.

6. Validate and iterate: Review the schema against the original requirements. Verify that all entities are represented, all relationships are correctly modeled, and no data integrity gaps exist. Adjust based on feedback.

Supported Technologies