title: Table with CANCAT key in MariaDB working in 10.0 but not later versions
body: <p>I am trying to upgrade from MariaDB 10.0 to 10.5 to use Galera Cluster. One of our tables has a key that the later versions won't accept. The error and table structure below.</p>
  <p>Refactoring code is a last resort, so if there is a table definition change that can fix the problem that would be <em><strong>fantastic!</strong></em></p>
  <p>Thank you!</p>
  <p>Error</p>
  <blockquote>
  <p>ERROR 1901 (HY000) at line 40239: Function or expression
  'concat(<code>tc_sequence_db_code</code>,<code>tc_sequence_prefix</code>,<code>tc_sequence_table_name</code>)'
  cannot be used in the GENERATED ALWAYS AS clause of <code>tc_sequence_id</code></p>
  </blockquote>
  <p>The table structure</p>
  <pre><code>CREATE TABLE `tc_sequence` (
    `tc_sequence_id` char(191) AS (concat(`tc_sequence_db_code`,`tc_sequence_prefix`,`tc_sequence_table_name`)),
    `tc_sequence_table_name` char(191) NOT NULL,
    `tc_sequence_db_code` char(2) NOT NULL DEFAULT '',
    `tc_sequence_prefix` char(5) NOT NULL DEFAULT '',
    `tc_sequence_next_id` int(11) NOT NULL DEFAULT 0,
    `dt_temp_id` varchar(36) DEFAULT NULL,
    `tc_sequence_trf_yn` tinyint(1) NOT NULL DEFAULT 0,
    UNIQUE KEY `tc_sequence_id` (`tc_sequence_id`),
    KEY `tc_sequence_table_name` (`tc_sequence_table_name`),
    KEY `dt_temp_id` (`dt_temp_id`),
    KEY `tc_sequence_trf_yn` (`tc_sequence_trf_yn`)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
  </code></pre>