MySql使用condiction离开了外连接

Question

I have two tables as

    student_info(id,mobile,cTId,lvDate)

    term_marks(tmId,stdId,cTId,marks,year)

Now I want to find out the all student id that are not present term_marks depending other checking, so I use this query but it returns all that matched and not matched two tables

     $sql = "select * from student_info si LEFT OUTER JOIN term_marks tm ON si.id=tm.stdId and si.cTId=tm.cTId AND tm.year=$year)
WHERE si.cTId=$cTId and si.lvDate=0";

Also I have tried it

      $sql = "select * from student_info si left outer JOIN term_marks tm where si.id=tm.stdId 
     and si.cTId=tm.cTId and si.cTId=$cTId and tm.year=$year and si.lvDate=0";  

Can you help me ?

Answer 1

SELECT si.* 
FROM student_info si 
WHERE si.cTId = $cTId 
  AND si.lvDate = 0
  AND si.id NOT IN 
  ( 
    SELECT tm.stdId 
    FROM term_marks tm 
    WHERE tm.year = $year
  )