Add unique constraint on moped_components_subcomponents table and comment

Author: mddilley

moped-database/migrations/1745881623802_decom_and_new_subcomponents/down.sql

@@ -1,4 +1,8 @@
--- if we delete the component tag in the future, we will soft delete and leave existing data intact
+-- if we delete the added component tag in the future, we will soft delete and leave existing data intact
+
+-- Remove unique constraint to allow for duplicate component/subcomponent associations
+ALTER TABLE moped_components_subcomponents
+DROP CONSTRAINT unique_component_subcomponents;
 
 -- Restore previous component tag name
 UPDATE moped_component_tags SET name = 'Upgrades Existing', type = 'Bikeways - Performance Measure', slug = 'bikeways_performance_measure_upgrades_existing'

moped-database/migrations/1745881623802_decom_and_new_subcomponents/up.sql

@@ -1,3 +1,14 @@
+-- Add unique constraint to ensure no duplicate component/subcomponent associations
+ALTER TABLE moped_components_subcomponents
+ADD CONSTRAINT unique_component_subcomponents
+UNIQUE (component_id, subcomponent_id);
+
+COMMENT ON CONSTRAINT unique_component_subcomponents ON moped_components_subcomponents IS 'Ensures no duplicate component/subcomponent associations';
+
+-- Alter moped_component_tags table to allow null names for new tags and updates to existing tags with empty names
+ALTER TABLE moped_component_tags
+ALTER COLUMN name DROP NOT NULL;
+
 -- Insert new tag to mark decommissioned components
 INSERT INTO moped_component_tags (name, type, slug) VALUES
 ('', 'Decommissioned / Upgraded Component', 'decommissioned_upgraded_component');