SAS,DATA PREPARATION - sas

Question

I have 5 columns .The columns are
date
stock[a,b,c,d,.]
qty_in[fixed number as in 10 qty came in for the stock on 1/1/2015]
qty_out[ went out /or got sold]
final_qty(qty_in -qty_out)
There are over 100 stocks and transaction for over 6 months duration,thus for the stocks on each day[for example,qty_in on 2/1/2015 is 10 then it should display the value of qty_in as sum of qty_in on 2/1/2015 +final_qty on 1/1/2015]for the same stock ] . How can i achieve this with sas.
Run this in sas
data testfile;
input date $ 1-10 stock $ 11-16 qty_in $17-20 qty_out $21-23 final_qty $24-26;
datalines;
1/1/2015 a 10 0 10
1/1/2015 b 20 4 16
1/1/2015 c 32 23 9
2/1/2015 a 10 /*this value should be= qty_in(2/1/2015 + final_qty 1/1/2015 i.e. 10+10=20*/
2/1/2015 b 20 /*this should be 20+16=36*/
2/1/2015 c 32
;

Answer 1

if you want to do this in a data step you first need to sort the data set by stock and by date. Also, start with just 4 columns and will compute the final col in the data set:
data stockout5;
set stockin4;
retain FIN_QTY;
by stock date;
if (first.stock) then FIN_QTY = INQTY - OUTQTY;
else FIN_QTY = FIN_QTY + INQTY - OUTQTY;
run;
let me know if this works for you. If you supply some test data with what you are starting with and what you want to end up with it would help. Your question is fine but it's not very clear unless you've worked with financial data before (imo)

Answer 2

From start to finish this should do what you're looking for. It's pretty straight forward let me know if you don't understand something. Note that 0 is added in for missing out values.
Data stock4;
format date date9.;
date = '1jan2015'd;
stock = "a";
in = 10;
out = 0 ;
output;
date = "1jan2015"d;
stock = "b";
in = 20;
out = 4;
output;
date = "1jan2015"d;
stock ="c";
in =32;
out=23;
output;
date="2jan2015"d;
stock = "a";
in = 10;
out=0;
output ;
date="2jan2015"d;
stock ="b";
in = 20;
out=0;
output;
date ="2jan2015"d;
stock = "c";
in=32;
out=0;
output;
run;
proc sort data=stock4;
by stock date;
run;
data stock5;
set stock4;
retain FIN_QTY;
by stock date;
if (first.stock) then FIN_QTY = IN - OUT;
else FIN_QTY = FIN_QTY + IN - OUT;
run;