sql insert into table from select without duplicates (need more then a DISTINCT)

Question

I am selecting multiple rows and inserting them into another table. I want to make sure that it doesn\'t already exists in the table I am inserting multiple rows into.

Answer 1

pseudo code for what might work

    insert into  select col1 etc 
from  
where .keycol not in 
(select source_table.keycol from source_table)