Split Records

I have a flat file with 2 columns

Id,loc

1,nj:ny:pa
2,pa
3,ca:tx:fl:nj

Second colum data is seperated by semi colon and can i have many locations for one id

Output i need is

1,nj
1,ny
1,pa
1,pa
3,ca
3,tx
3,fl
3,nj

I need to split the record in to multiple records.

please help me how to proceed

Your sample output is incorrect in line 4, should be 2,pa. This will yield the corrected output from your input:

awk -F"," -vOFS="," 'NR>1 {n=split($2, co, ":"); for (i=1;i<=n;i++) print $1, co}' infile