MDL-69687 DB: Add API for deleting data based on subquery

The new API works on normal databases (by deleting data based on the
subquery) and also on MySQL (by deleting the data using a weird join
on the subquery).

lib/dml/moodle_database.php

@@ -2038,6 +2038,29 @@ abstract class moodle_database {
         return $this->delete_records_select($table, $select, $params);
     }
 
+    /**
+     * Deletes records from a table using a subquery. The subquery should return a list of values
+     * in a single column, which match one field from the table being deleted.
+     *
+     * The $alias parameter must be set to the name of the single column in your subquery result
+     * (e.g. if the subquery is 'SELECT id FROM whatever', then it should be 'id'). This is not
+     * needed on most databases, but MySQL requires it.
+     *
+     * (On database where the subquery is inefficient, it is implemented differently.)
+     *
+     * @param string $table Table to delete from
+     * @param string $field Field in table to match
+     * @param string $alias Name of single column in subquery e.g. 'id'
+     * @param string $subquery Subquery that will return values of the field to delete
+     * @param array $params Parameters for subquery
+     * @throws dml_exception If there is any error
+     * @since Moodle 3.10
+     */
+    public function delete_records_subquery(string $table, string $field, string $alias,
+            string $subquery, array $params = []): void {
+        $this->delete_records_select($table, $field . ' IN (' . $subquery . ')', $params);
+    }
+
     /**
      * Delete one or more records from a table which match a particular WHERE clause.
      *