Before updates to NHTSA

data/make-model-import/migrations/001_create_vehicle_database.sql

@@ -27,6 +27,8 @@ CREATE TABLE engines (
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
 );
+-- Prevent duplicate engine display names (case-insensitive)
+CREATE UNIQUE INDEX IF NOT EXISTS uq_engines_name_lower ON engines (LOWER(name));
 
 CREATE INDEX idx_engines_displacement ON engines(displacement);
 CREATE INDEX idx_engines_config ON engines(configuration);
@@ -40,6 +42,8 @@ CREATE TABLE transmissions (
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
 );
+-- Prevent duplicate transmission display names (case-insensitive)
+CREATE UNIQUE INDEX IF NOT EXISTS uq_transmissions_type_lower ON transmissions (LOWER(type));
 
 CREATE INDEX idx_transmissions_type ON transmissions(type);
 
@@ -55,6 +59,10 @@ CREATE TABLE vehicle_options (
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
 );
+-- Prevent duplicate vehicle option rows
+CREATE UNIQUE INDEX IF NOT EXISTS uq_vehicle_options_full ON vehicle_options (
+    year, make, model, trim, engine_id, transmission_id
+);
 
 -- Indexes for cascading dropdown performance
 CREATE INDEX idx_vehicle_year ON vehicle_options(year);