Editing 排除 MySQL 技術疑難問題 (section)

=== 錯誤 1170: 在鍵規格中使用 BLOB/TEXT 欄位且沒有鍵長 ===
情況
* 嘗試建立新表格時的 SQL 語法

<pre>
DROP TABLE IF EXISTS `my_table`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `my_table` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(500) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `url` text COLLATE utf8mb4_unicode_ci NOT NULL,
  `status` tinyint(2) unsigned NOT NULL DEFAULT 1,
  PRIMARY KEY (`job_id`),
  UNIQUE KEY `url` (`url`) USING HASH
) ENGINE=InnoDB AUTO_INCREMENT=3573 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*!40101 SET character_set_client = @saved_cs_client */;
</pre>

解決方案：在鍵規格中使用 BLOB/TEXT 欄位並指定鍵長，例如 {{kbd | key=`url`(500)}}
<pre>
DROP TABLE IF EXISTS `my_table`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `my_table` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(500) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  `url` text COLLATE utf8mb4_unicode_ci NOT NULL,
  `status` tinyint(2) unsigned NOT NULL DEFAULT 1,
  PRIMARY KEY (`id`),
  UNIQUE KEY `url` (`url`(500))
) ENGINE=InnoDB AUTO_INCREMENT=3573 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*!40101 SET character_set_client = @saved_cs_client */;
</pre>