php - 如何等于另一个表中的两个不同 ID？

Question

select student.student_fname,
student.student_mname,
student.student_lname, logs.time, logs.transaction,logs.entity_type,prof.professor_fname,prof.professor_mname,prof.professor_lname 
from student_tbl as student,
logs_tbl as logs,
professor_tbl as prof 
where student.student_id=logs.entity_id 
and prof.professor_id=logs.entity_id
and logs.date ='$date_today' 
and logs.course_id='$course' 
and logs.sections_id='$sections'
and logs.rooms_id='$room'  
group by logs.date, 
logs.term, 
logs.course_id, 
logs.entity_id  
order by logs.logs_id asc 

在 student_tbl 和 professor_tbl 中，我有 student_id 和 professor_id 等于 logs_tbl 的 entity_id。我如何将来自不同表的这两个 id 与 logs_tbl 中的 entity_id 进行比较？这是唯一给我错误的行。或者你有什么建议？除了sql注入(inject)的东西

更新

我有 student_tbl 列有:student_id、student_fname、student_mname、student_lname。我也有 professor_tbl，列有:professor_id、professor_fname、professor_mname、professor_lname，我的第三个表是 logs_tbl，列有:entity_id (这是 student_id 和 professor_id 相等的地方)、course_id、rooms_id、sections_id、time、date、transaction、entity_type。这就是我要显示的内容:

• student_fname/professor_fname(取决于entity_id)
• student_mname/professor_mname(取决于entity_id)
• student_lname/professor_lname(取决于entity_id)
• 时间
• 交易
• 实体类型

示例数据展示:

• 克里斯 |康斯塔 |乐家| 11:30 |在 |学生
• 鲍勃 |琼斯 |马利 | 11:32 |在 |学生
• 罗纳德 |詹姆斯 |里昂 | 11:35 |在 |教授
  • 克里斯 |康斯塔 |乐家| 1:00 |出来 |学生
• 鲍勃 |琼斯 |马利 | 1:05 |出来 |学生
• 罗纳德 |詹姆斯 |里昂 | 1:06 |出来 |教授

Answer 1

  select student.student_fname,  student.student_mname, student.student_lname, logs.time, logs.transaction,logs.entity_type
          from student_tbl as student inner join logs_tbl as logs on student.student_id=logs.entity_id  
     where   logs.date ='$date_today' 
                and logs.course_id='$course' 
                and logs.sections_id='$sections'
                and logs.rooms_id='$room'  
                group by logs.date,  logs.term, 
                logs.course_id, 
                logs.entity_id   


    UNION  

      select prof.professor_fname,prof.professor_mname,prof.professor_lname , logs.time, logs.transaction,logs.entity_type
          from   professor_tbl as prof inner join logs_tbl as logs   on prof.professor_id=logs.entity_id
             where   logs.date ='$date_today' 
                and logs.course_id='$course' 
                and logs.sections_id='$sections'
                and logs.rooms_id='$room'  
                group by logs.date,  logs.term, 
                logs.course_id, 
                logs.entity_id