Laravel 日期比较不适用于 created_at 列

Question

我编写了一个查询，用于检查在对话中的用户删除后写入对话的消息。这是我的查询：

$messages = DB::table('conversations')
                    ->where('conversations.id', $conversation->id)
                    ->join('messages', 'messages.conversation_id', '=', 'conversations.id')
                    ->join('deleted_conversations', 'deleted_conversations.conversation_id', '=', 'conversations.id')
                    ->where('messages.created_at', '>=', 'deleted_conversations.created_at')
                    ->orderBy('messages.created_at', 'desc')
                    ->select('messages.*')
                    ->get()
                    ->all();

但每次我尝试使用where('messages.created_at, '<', 'deleted_conversations_created_at 语句运行此查询时，如果没有精确检查日期。为什么？

这里是迁移：

Schema::create('conversations', function (Blueprint $table) {
            $table->id();
            $table->integer('sender_id');
            $table->integer('receiver_id');
            $table->enum('status', ['read', 'unread']);
            $table->timestamps();
        });

 Schema::create('messages', function (Blueprint $table) {
            $table->id();
            $table->integer('conversation_id');
            $table->integer('sender_id');
            $table->string('message');
            $table->timestamps();
        });

Schema::create('deleted_conversations', function (Blueprint $table) {
            $table->id();
            $table->integer('conversation_id');
            $table->integer('user_id');
            $table->timestamps();
        });

deleted_conversations 表

id	conversation_id	user_id	created_at	updated_at
1	1	2	2021-02-28 11:26:36	2021-02-28 11:30:45

对话表

id	sender_id	user_id	receiver_id	status	created_at	updated_at
1	1	1	2	unread	2021-02-28 11:07:09	2021-02-28 11:31:50

消息表

id	conversation_id	sender_id	message	created_at	updated_at
1	1	1	S.A	2021-02-28 00:00:00	2021-02-28 00:00:00
2	1	2	A.S	2021-02-28 00:00:00	2021-02-28 00:00:00

Answer 1

当你想添加一个where子句的值是另一列时，你需要使用whereColumn()：

->whereColumn('messages.created_at', '>=', 'deleted_conversations.created_at')