CREATE TABLE knowledge_items (
  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  tenant_id BIGINT UNSIGNED NOT NULL,
  scenario_id BIGINT UNSIGNED NOT NULL,
  item_key VARCHAR(64) NOT NULL,
  name VARCHAR(128) NOT NULL,
  type VARCHAR(64) NOT NULL,
  content JSON NOT NULL,
  status VARCHAR(24) NOT NULL DEFAULT 'active',
  sort_order INT NOT NULL DEFAULT 0,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  updated_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (id),
  UNIQUE KEY uk_knowledge_items_key (scenario_id, item_key),
  KEY idx_knowledge_items_type (tenant_id, scenario_id, type, status),
  CONSTRAINT fk_knowledge_items_tenant FOREIGN KEY (tenant_id) REFERENCES tenants(id),
  CONSTRAINT fk_knowledge_items_scenario FOREIGN KEY (scenario_id) REFERENCES scenarios(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE knowledge_relations (
  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  tenant_id BIGINT UNSIGNED NOT NULL,
  scenario_id BIGINT UNSIGNED NOT NULL,
  from_knowledge_id BIGINT UNSIGNED NOT NULL,
  relation_type VARCHAR(64) NOT NULL,
  to_knowledge_id BIGINT UNSIGNED NOT NULL,
  `condition` JSON NOT NULL,
  sort_order INT NOT NULL DEFAULT 0,
  created_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  updated_at DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (id),
  UNIQUE KEY uk_knowledge_relation (scenario_id, from_knowledge_id, relation_type, to_knowledge_id),
  KEY idx_knowledge_relation_from (tenant_id, scenario_id, from_knowledge_id, relation_type),
  CONSTRAINT fk_knowledge_relations_tenant FOREIGN KEY (tenant_id) REFERENCES tenants(id),
  CONSTRAINT fk_knowledge_relations_scenario FOREIGN KEY (scenario_id) REFERENCES scenarios(id) ON DELETE CASCADE,
  CONSTRAINT fk_knowledge_relations_from FOREIGN KEY (from_knowledge_id) REFERENCES knowledge_items(id) ON DELETE CASCADE,
  CONSTRAINT fk_knowledge_relations_to FOREIGN KEY (to_knowledge_id) REFERENCES knowledge_items(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;