title: how to delete rows in a single table involving multiple table
body: <p>hi i'm just new to sql and i have a hard time deleting records. i need to   Delete all the records from subjcode table where the teacher is “MARSHALL”. i used this query but i doesn't work:</p>
  
  <pre><code>delete
  from subjcode
  where (
          select sa.sno
          from subjcode sa,
              teacher,
              course
          where teacher.tname = 'MARSHALL'
              and teacher.tno = course.tno
              and course.cno = sa.cno
          ) = subjcode.sno;
  </code></pre>
  
  <p>and there is the table and its columns:</p>
  
  <pre><code>subjcode: sno,cno,score
  
  course: cno,tno,cname
  
  teacher:tno,tname
  </code></pre>
  
  <p>i know that all i need is just the tname,tno, and the cno but i don't know the proper query. please help me thanks</p>