如何選擇使用內部聯接？

Question

我正在嘗試使用查詢生成器進行INNER JOIN 。 但是，當我嘗試在表中檢索所有內容時，它說缺少參數2。

第63行的C：\\ Users \\ JohnFrancis \\ LaravelFrancis \\ app \\ Http \\ Controllers \\ DocumentController.php中調用的Illuminate \\ Database \\ Query \\ Builder :: join（）缺少參數2

我不知道我的ALIAS是否錯誤，但我只是基於SQL查詢。 見下文。

的SQL

SELECT D.title, C.category_type, U.username, DU.dateReceived FROM document_user DU
#1st JOIN
INNER JOIN users U ON DU.sender_id = U.id
#2nd JOIN
INNER JOIN documents D ON DU.document_id = D.id
#3rd JOIN
INNER JOIN categories C ON C.id = D.category_id;

結果

數據庫圖

控制者

public function showDocuments()
{

    $documentsList = DB::table('document_user')
        ->select('D.title', 'C.category_type', 'U.username', 'DU.dateReceived')
        ->join('users AS U')->on('DU.sender_id', '=', 'U.id')
        ->join('documents AS D')->on('DU.document_id', '=', 'D.id')
        ->join('categories AS C')->on('C.id', '=', 'D.category_id')
        ->where('sender_id', '!=', Auth::id()->get());

    return view ('document.show')->with('documentsList', $documentsList);
}

我想檢索但當前用戶除外 。 如您所見，我添加了where子句。 ->where('sender_id', '!=', Auth::id()->get());

視圖

<table class = "table">

        <thead>
            <tr>
                <th>Title</th>
                <th>Category</th>
                <th>Sender</th>
                <th>Date Received</th>
                <th>Action</th>
            </tr>               
        </thead>

        <tbody>
        @foreach ($documentsList as $list)
            <tr class = "info">
            <td>{{ $list->title }}</td>
            <td>{{ $list->category_type }}</td>
            <td>{{ $list->username }}</td>
            <td>{{ $list->dateReceived }}</td>
            <td><a href = "#"><button type = "submit" class = "btn btn-info">Read</button></a></td>
            </tr>
        @endforeach
        </tbody>

</table>

Answer 1

看了很多博客后，我發現本課很有用。

http://jpcamara.com/selecting-carefully-laravel-joins/

$documentsList = DB::table('document_user')->select('documents.title', 'categories.category_type', 'users.username', 'document_user.dateReceived')
        ->join('users', 'users.id', '=', 'document_user.sender_id')
        ->join('documents', 'documents.id', '=', 'document_user.document_id')
        ->join('categories', 'categories.id', '=', 'documents.category_id')
        ->where('sender_id', '!=', Auth::id())->get();