-- 只读：按证面品名归纳候选证用品类名（上线前人工建品类参考）
-- 不写库。执行后人工创建 pl_cert_category、关联产品，并回填证件 customer_id/category_id，再配置 effective_at。
SET NAMES utf8mb4;

SELECT
  TRIM(product_name_on_cert) AS candidate_category_name,
  COUNT(*) AS cert_count,
  SUM(CASE WHEN cert_type = 'purchase' THEN 1 ELSE 0 END) AS purchase_count,
  SUM(CASE WHEN cert_type = 'transport' THEN 1 ELSE 0 END) AS transport_count
FROM (
  SELECT 'purchase' AS cert_type, product_name_on_cert
  FROM pl_purchase_cert
  WHERE del_flag = 0
    AND product_name_on_cert IS NOT NULL
    AND TRIM(product_name_on_cert) <> ''
  UNION ALL
  SELECT 'transport' AS cert_type, product_name_on_cert
  FROM pl_transport_cert
  WHERE del_flag = 0
    AND product_name_on_cert IS NOT NULL
    AND TRIM(product_name_on_cert) <> ''
) t
GROUP BY TRIM(product_name_on_cert)
ORDER BY cert_count DESC, candidate_category_name;