Insert unique rows in temp table

i have temp table name "#TempResult" with column names Memberid,Month,Year. Consider this temp table alredy has some rows from previuos query. I have one more table name "Rebate" which also has columns MemberID,Month, Year and some more columns. Now i wanted to insert rows from "Rebate" Table into Temp Table where MemberID.Month and Year DOES NOT exist in Temp table.

MemberID + Month + Year should ne unique in Temp table

I don't think what you are doing is valid because a local temp table scope is very limited, but if it valid it will be covered in the link below by one of the best minds in T-SQL. Hope this helps.

http://www.awprofessional.com/articles/article.asp?p=25288&seqNum=4&rl=1