如何在mySql

Question

我必须使用表格job_postings和job_applies。如何获得用户尚未申请的所有工作？

以下是我的job_postings表的列：

id, user_id, title, description, duties, salary, child_count, benefits, created_at, updated_at

以下是job_applies表

的列

user_id, posting_id, status, created_at, updated_at

我尝试了什么：

  $job_postings =  DB::table('job_postings')
        ->select(
          'job_postings.title',
          'job_postings.description',
          'job_postings.duties',
          'job_postings.salary',
          'job_postings.child_count',
          'job_postings.benefits',
          'job_postings.created_at',
          'job_postings.id AS posting_id',
          'job_postings.user_id')
        ->join('job_applies', 'job_applies.posting_id', '!=', 'job_postings.id')
        ->where('job_applies.user_id', "=" , user()->id)
        ->get();

Answer 1

在Mysql中你应该写（用你的字段列表替换*）。你可以适应你的语言

 SELECT * 
 FROM JOB_POSTING A
 LEFT JOIN JOB_APPLIES B ON B.POSTING_ID = A.ID AND B.USER_ID = A.USER_ID
 WHERE B.POSTING_ID IS NULL

或

 SELECT * 
 FROM JOB_POSTING A
 WHERE NOT EXISTS (SELECT 1 FROM JOB_APPLIES B WHERE B.POSTING_ID = A.ID  AND B.USER_ID = A.USER_ID)