select M1.Name AS Name1,M2.Name AS Name2,Ma.Content from 
MemberAction Ma
left join Member M1 ON M1.ID = Ma.MemberFromID
left join Member M2 ON M2.ID = Ma.MemberToID

------解决方案--------------------
SELECT ( select b.name from member b where a.MemberFromID  = b.id ) as MemberFromID ,
       ( select b.name from member b where a.MemberToID = b.id ) as MemberToID ,
       Content  
FROM memberaction a  

试试吧。