perf: 消息列表需支持多个置顶

database/migrations/2022_02_18_095253_web_socket_dialog_users_add_top_at.php

@@ -0,0 +1,34 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class WebSocketDialogUsersAddTopAt extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('web_socket_dialog_users', function (Blueprint $table) {
+            if (!Schema::hasColumn('web_socket_dialog_users', 'top_at')) {
+                $table->timestamp('top_at')->nullable()->after('top')->comment('置顶时间');
+            }
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('web_socket_dialog_users', function (Blueprint $table) {
+            $table->dropColumn("top_at");
+        });
+    }
+}