data z1;
    put _ALL_;
    set sashelp.class;
    put _ALL_;
        col1 = weight / 2;
        put _ALL_;
run;

data z2;
    set sashelp.cars end = koniec;
    *retain total 0; /* zapamietaj total = 0*/
    *total = total + invoice;

    total + invoice;
    keep total;
    if koniec then output;
run;

*przetwarzanie w grupach
zlicz liczbê aut dla każdej marki;

proc sort data = sashelp.cars out = cars;
    by make;
run;

data z3;
    set cars;
    by make;
    col1 = first.make;
    col2 = last.make;
run;

data z4;
    set sashelp.cars;
    by make;
    if first.make then do
        licznik = 0;
        suma = 0;
    end;
    licznik + 1;
    suma + invoice;
    if last.make then output;
    keep make licznik suma;
run;

*na podstawie sashelp.air zliczyĉ przewozy w latach;
data z5;
    set sashelp.air;
    rok = year(date);
run;

data z6;
    set z5;
    by rok;
    if first.rok then suma = 0;
    suma + air;
    if last.rok then output;
    keep rok suma;
run;

*podaj 3 najdroższe auta dla każdej marki;
proc sort data = sashelp.cars out = cars;
    by make descending invoice;
run;

data z7;
    set cars;
    by make;
    if first.make then licznik = 0;
    licznik + 1;
    if licznik <= 3 then output;
run;

proc sort data = sashelp.class out = class;
    by descending height;
run;

data zz1;
    set class;
    by sex;
    *if first.sex then output;
run;

data zz2;
    set sashelp.class;
    retain min min(height);
    delta_height = height - min;
run;