-- =============================================================================
-- migrate_notice_receiver_ids_text.sql
-- t_notice.ReceiverIds：JSON → TEXT，保证广播（[]）与定向名单可用字符串条件查询
-- 可重复执行
-- =============================================================================
SET @db := DATABASE();

SET @col_type := (
  SELECT DATA_TYPE
    FROM information_schema.COLUMNS
   WHERE TABLE_SCHEMA = @db
     AND TABLE_NAME = 't_notice'
     AND COLUMN_NAME = 'ReceiverIds'
   LIMIT 1
);

SET @sql := IF(
  @col_type IS NOT NULL AND LOWER(IFNULL(@col_type, '')) = 'json',
  'ALTER TABLE `t_notice`
     MODIFY COLUMN `ReceiverIds` TEXT NOT NULL COMMENT ''接收对象ID列表(JSON数组字符串)''',
  'SELECT ''t_notice.ReceiverIds already text or missing'' AS info'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;