how to delete a group of observations based on certain conditions

[abc44]

Hi all, 

I would like to remove a group of observations from my dataset if the first value does not meet a certain criteria. For example, I would like to delete all entries for a certain subject ID when the first QC value is 0. If the first QC value is 1, then I do not want to delete any entries from this subject ID. 

Here is an example of what my data looks like (envision additional columns with various outcome variables): 

ID    QC 

1      1

1      0

1      1

1      1

2      0

2      0

2      1

2      1 

3      1

3      0

3      1

I would like achieve the following:

ID    QC

1      1

1      0

1      1

1      1

3      1

3      0

3      1

*subject with ID=2 was deleted because the first observation did not meet quality control (QC=0). 

Thanks in advance!

[novinosrin · Accepted solution]

data have;
input ID    QC ;
cards;
1      1
1      0
1      1
1      1
2      0
2      0
2      1
2      1 
3      1
3      0
3      1
;

data want;
set have;
by id;
retain flag;
if first.id then call missing(flag);
if first.id and qc=1 then flag=1;
if flag;
drop flag;
run;

[abc44]

Thanks so much!