insert if not exists in sqlite with vb.net

Question

I have records from server that I want to copy, so I used datareader to select all, during selection the insert also process. This is the pseudo code:

while datareader.read
        For f As Integer = 0 To datareader.FieldCount - 1
                Values = Values & datareader.GetValue(f)
        Next
    Dim ss as string ="Insert into xtable(a,b,c,d,e,f) select " & values & " where not Exist (select * from xtable)" ''//is this right?
    Dim sc as new sqliteCommand(ss,mycon)
    sc.ExecuteNonQuery
    End While
    sc.dispose

What is the exact sql statement to insert only if record doesn't exist in my current table?

I used some of this code, but a filter was defined: like x What if I just want to insert records that doesn't exist in the table I want.

Dim ss As String = "insert into xtable(x,y,z) select $x, $y,$z 
where not exists (select 1 from xtable where x=$x)"

Answer 1

Try this:

if not exists(select 1 from xtable)
   begin
       insert into xtable(x,y,z) select $x, $y,$z from xtable
   end

I don't think the above will work, but this link should give you the answer you're looking for.