如何将 sql 转换为查询生成器 laravel

Question

谁能帮我将此 SQL 转换为查询生成器！

SELECT topwords.*, 
       mw.word AS my_word 
FROM   topwords 
       LEFT JOIN (SELECT DISTINCT words.word 
                  FROM   definition_word 
                         JOIN words 
                           ON words.id = definition_word.word_id 
                  WHERE  definition_word.user_id = $user) AS mw 
              ON topwords.word = mw.word 

我对如何在 leftjoin 中使用子查询有疑问！

我尝试过这样的事情，但它有错误！ See error as image

DB::table('topwords')
                    ->leftJoin(DB::raw("SELECT DISTINCT
                    words.word
                    FROM definition_word 
                    JOIN words ON words.id = definition_word.word_id
                    WHERE definition_word.user_id = $user as mw"),"topwords.word", "=", "mw.word" )
                    ->select(
                        "topwords.*",
                        "mw.word AS my_word"
                    )->orderBy('id','desc')->paginate(15);

Answer 1

可以使用Join Sub查询官方文档subquery-joins

$mw = DB::table('words')
        ->select('DISTINCT words.word')
        ->join('definition_word', function($join) use ($user)
        {
            $join->on('wordss.id', '=', 'definition_word.word_id')
                 ->where('definition_word.user_id',  $user);
        });
        
$topwords = DB::table('topwords')
        ->joinSub($mw, 'mw',function ($join) {
            $join->on('topwords.word', '=', 'mw.word');
        })
        ->select('topwords.*','mw.word AS my_word')
        ->orderBy('id','desc')
        ->paginate(15);

Answer 2

由于分页和聚合

，您会遇到此错误

尝试使用 LengthAwarePaginator 进行自定义分页

这里是示例：Laracast

所以你需要做这样的事情：

  $query = DB::table('topwords')
                        ->leftJoin(DB::raw("SELECT DISTINCT
                        words.word
                        FROM definition_word 
                        JOIN words ON words.id = definition_word.word_id
                        WHERE definition_word.user_id = $user as mw"),"topwords.word", "=", "mw.word" )
                        ->select(
                            "topwords.*",
                            "mw.word AS my_word"
                        );
    
    
    $paginator = new LengthAwarePaginator($query->get(), $query->count(), $request->input('per_page', 15), $request->input('page', 1));

然后就可以在集合中使用了