How to fill this missing Value?

[Ganeshk]

Hi,

I have table as shown below, 

Id	Date	Category	Price
1	1/1/2001	Jam	12
2	1/2/2001	Jam
3	1/3/2001	Jam
4	1/4/2001	Glocose	13
5	1/5/2001	Jam	15
6	1/6/2001	Jam
7	1/7/2001	Glocose	16
8	1/8/2001	Glocose
9	1/9/2001	Glocose

need to fill missing value as show below:

Id	Date	Category	Price
1	1/1/2001	Jam	12
2	1/2/2001	Jam	12
3	1/3/2001	Jam	12
4	1/4/2001	Glocose	13
5	1/5/2001	Jam	15
6	1/6/2001	Jam	15
7	1/7/2001	Glocose	16
8	1/8/2001	Glocose	16
9	1/9/2001	Glocose	16

[RW9]

Post test data in the form of a datastep!!

As such I am jsut guessing:

data want;
  set have (rename=(price=old_price));
  retain price;
  if old_price ne . then price=old_price;
run;