SET @fk_order_item_order = (
  SELECT CONSTRAINT_NAME
  FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
  WHERE TABLE_SCHEMA = DATABASE()
    AND TABLE_NAME = 'orderitem'
    AND REFERENCED_TABLE_NAME = 'order'
  LIMIT 1
);

SET @sql = IF(
  @fk_order_item_order IS NULL,
  'SELECT 1',
  CONCAT('ALTER TABLE `orderitem` DROP FOREIGN KEY `', @fk_order_item_order, '`')
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SET @fk_order_item_product = (
  SELECT CONSTRAINT_NAME
  FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
  WHERE TABLE_SCHEMA = DATABASE()
    AND TABLE_NAME = 'orderitem'
    AND REFERENCED_TABLE_NAME = 'supplier_product'
  LIMIT 1
);

SET @sql = IF(
  @fk_order_item_product IS NULL,
  'SELECT 1',
  CONCAT('ALTER TABLE `orderitem` DROP FOREIGN KEY `', @fk_order_item_product, '`')
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SET @fk_order_user = (
  SELECT CONSTRAINT_NAME
  FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
  WHERE TABLE_SCHEMA = DATABASE()
    AND TABLE_NAME = 'order'
    AND REFERENCED_TABLE_NAME = 'User'
  LIMIT 1
);

SET @sql = IF(
  @fk_order_user IS NULL,
  'SELECT 1',
  CONCAT('ALTER TABLE `order` DROP FOREIGN KEY `', @fk_order_user, '`')
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

DROP TABLE IF EXISTS `orderitem`;
DROP TABLE IF EXISTS `order`;