-- 偏远附加费按重量区间和邮编命中。已有库可重复执行。
SET NAMES utf8mb4;

SET @sql = (
  SELECT IF(
    COUNT(*) = 0,
    'ALTER TABLE pay_surcharge ADD COLUMN weight_min decimal(12,3) DEFAULT NULL COMMENT ''适用重量下限KG，空表示不限'' AFTER calc_param',
    'SELECT 1'
  )
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'pay_surcharge' AND COLUMN_NAME = 'weight_min'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SET @sql = (
  SELECT IF(
    COUNT(*) = 0,
    'ALTER TABLE pay_surcharge ADD COLUMN weight_max decimal(12,3) DEFAULT NULL COMMENT ''适用重量上限KG，空表示不限'' AFTER weight_min',
    'SELECT 1'
  )
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'pay_surcharge' AND COLUMN_NAME = 'weight_max'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SET @sql = (
  SELECT IF(
    COUNT(*) = 0,
    'ALTER TABLE pay_surcharge ADD COLUMN postcode_param varchar(1000) DEFAULT NULL COMMENT ''偏远邮编规则，如07,35或IV,KA27-28'' AFTER weight_max',
    'SELECT 1'
  )
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'pay_surcharge' AND COLUMN_NAME = 'postcode_param'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;