One SQL statement queries two fields in both tables

First, the problem is described, and the Student table has field startid,endid. The ID in the Garde table needs to correspond to the Startid in the student table or Endid in the student table to find the Name field in the Grade table, and then the problem is, what if I need a SQL sentence to find out the two data in the Garde table? (The association field of two tables is SID)

Sql= "Select B.name,c.name as Name2

From student A,garde B,grade C

where A.sid=b.sid

and A.sid=c.sid and A.startid=b.id

and A.endid=b.id "

One SQL statement queries two fields in both tables