Question

Im trying to copy row from table to another using 2 coluom only as the tow table schema is not identical ,
am getting this error

Operand should contain 1 column(s)

Any tips whats wrong with my statement ?

 Insert table1 ( screenname,list_id )
  Select screenname,list_id
 From table2 As T1
 Where Not Exists    (
                Select 1
                From table1 As T2
                Where 
               (T2.screenname = T1.screenname,T2.list_id = T1.list_id)
                )

Answer 1

try to change where condition from (T2.screenname = T1.screenname,T2.list_id = T1.list_id) to (T2.screenname = T1.screenname AND T2.list_id = T1.list_id)

(note AND keyword instead of comma)