-- Fix 1452: empty orphan prc_order_ext then add FK to prc_order
-- Confirm DB = bms, then run in order.

SELECT DATABASE() AS current_db;
SELECT COUNT(*) AS ext_rows_before FROM prc_order_ext;
SELECT COUNT(*) AS order_rows FROM prc_order;

TRUNCATE TABLE prc_order_ext;

SELECT COUNT(*) AS ext_rows_after FROM prc_order_ext;

-- Drop failed/partial FK name if present (ignore error if missing)
SET @fk := (
  SELECT CONSTRAINT_NAME FROM information_schema.TABLE_CONSTRAINTS
  WHERE TABLE_SCHEMA = DATABASE()
    AND TABLE_NAME = 'prc_order_ext'
    AND CONSTRAINT_TYPE = 'FOREIGN KEY'
    AND CONSTRAINT_NAME = 'fk_order_ext_order'
  LIMIT 1
);
SET @sql := IF(
  @fk IS NOT NULL,
  'ALTER TABLE prc_order_ext DROP FOREIGN KEY fk_order_ext_order',
  'SELECT 1'
);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;

ALTER TABLE prc_order_ext
  ADD CONSTRAINT fk_order_ext_order
  FOREIGN KEY (order_id) REFERENCES prc_order (order_id) ON DELETE CASCADE;