hi all,

my mstr table have more than 20000 records, every time i run this code under mean increase table mstr,
this code take more one minute , is there any thing i must modify to make it faster.

insert INTO mstr ;
 Select * From main2 Where ;
  DtoS(file_date) + DtoS(intervdate)+Str(num) Not In ;
   (Select  DtoS(file_date) + DtoS(intervdate)+Str(num) ;
    From mstr)

thanks