Add command to fix inconsistent groups.

app/Console/Commands/Correction/FixGroupAccounts.php

@@ -0,0 +1,60 @@
+<?php
+declare(strict_types=1);
+
+namespace FireflyIII\Console\Commands\Correction;
+
+use DB;
+use FireflyIII\Events\UpdatedTransactionGroup;
+use FireflyIII\Handlers\Events\UpdatedGroupEventHandler;
+use FireflyIII\Models\TransactionGroup;
+use FireflyIII\Models\TransactionJournal;
+use Illuminate\Console\Command;
+
+/**
+ * Class FixGroupAccounts
+ */
+class FixGroupAccounts extends Command
+{
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Unify the source / destination accounts of split groups.';
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'firefly-iii:unify-group-accounts';
+
+    /**
+     * Execute the console command.
+     *
+     * @return int
+     */
+    public function handle(): int
+    {
+        // select transaction_group_id, count(transaction_group_id) as the_count from transaction_journals group by transaction_group_id having the_count > 1
+        $groups = [];
+        $res    = TransactionJournal
+            ::groupBy('transaction_group_id')
+            ->get(['transaction_group_id', DB::raw('COUNT(transaction_group_id) as the_count')]);
+        foreach ($res as $journal) {
+            if ((int) $journal->the_count > 1) {
+                $groups[] = (int) $journal->transaction_group_id;
+            }
+        }
+        $handler = new UpdatedGroupEventHandler;
+        foreach($groups as $groupId) {
+            $group = TransactionGroup::find($groupId);
+            $event = new UpdatedTransactionGroup($group);
+            $handler->unifyAccounts($event);
+        }
+
+        $this->line('Updated inconsistent transaction groups.');
+
+
+        return 0;
+    }
+}