Joachim Noreiko · 51024445
--- a/core/modules/mysql/tests/src/Kernel/mysql/SqlModeTest.php
+++ b/core/modules/mysql/tests/src/Kernel/mysql/SqlModeTest.php
    // based on databaseType() rather than 'driver', but here all we have to go
    // on is 'driver'.
    if ($info['default']['driver'] === 'mysql') {
-      $info['default']['init_commands']['sql_mode'] = "SET sql_mode = ''";
+      $info['default']['sql_mode_options']['ANSI'] = FALSE;
--- a/core/modules/mysql/src/Driver/Database/mysql/Connection.php
+++ b/core/modules/mysql/src/Driver/Database/mysql/Connection.php
      'init_commands' => [],
    ];

-    $connection_options['init_commands'] += [
-      'sql_mode' => "SET sql_mode = 'ANSI,TRADITIONAL'",
+    // Emit a deprecation warning if sql_mode is in the init commands.
+    if (isset($connection_options['init_commands']['sql_mode'])) {
+      @trigger_error("The 'sql_mode' database command is deprecated in drupal:11.1.0 and will be removed in drupal:12.0.0. Use an array of options in 'sql_mode_options' instead. See https://www.drupal.org/node/3403416", E_USER_DEPRECATED);
--- a/core/modules/mysql/src/Driver/Database/mysql/Connection.php
+++ b/core/modules/mysql/src/Driver/Database/mysql/Connection.php
      'init_commands' => [],
    ];

-    $connection_options['init_commands'] += [
-      'sql_mode' => "SET sql_mode = 'ANSI,TRADITIONAL'",
+    // Emit a deprecation warning if sql_mode is in the init commands.
+    if (isset($connection_options['init_commands']['sql_mode'])) {
+      @trigger_error("The 'sql_mode' database command is deprecated in drupal:11.1.0 and will be removed in drupal:12.0.0. Use an array of options in 'sql_mode_options' instead. See https://www.drupal.org/node/3403416", E_USER_DEPRECATED);
+    }
+
+    // If the user has set sql_mode_options, then ignore sql_mode.
+    if (isset($connection_options['sql_mode_options'])) {
+      unset($connection_options['init_commands']['sql_mode']);
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
 * Advanced users can add or override initial commands to execute when
 * connecting to the database server, as well as PDO connection settings. For
 * example, to enable MySQL SELECT queries to exceed the max_join_size system
- * variable, and to reduce the database connection timeout to 5 seconds:
+ * variable, and configure MariaDB to interpret GROUP BY clauses the same way
+ * that MySQL does, and to reduce the database connection timeout to 5 seconds:
 * @code
 * $databases['default']['default'] = [
 *   'init_commands' => [
 *     'big_selects' => 'SET SQL_BIG_SELECTS=1',
 *   ],
+ *   'sql_mode_options' => [
+ *     'ONLY_FULL_GROUP_BY' => TRUE,