my @ins_fields= ("log");
my @ins_values= ("''");
for (1..25) {
    $writer[$_ -1] = "value of writer". ($_-1) ;
    push @ins_fields, "log$_";
    push @ins_values, $writer[$_ -1];
}
my $ins_fields = join ",", @ins_fields;
my $ins_values = join ",", @ins_values;
print "INSERT INTO $log ($ins_fields)\nVALUES ($ins_values)";