How to assign value from isql to UNIX variable

I want output to be assigned to UNIX variables

echo "Enter RRS ID: "
read rrs
isql -SPROD_DDS -USYBUSER -PSYBPASS -b -osfg.out << EOF
use sip
go
set nocount on
select issuerId,
legalStructTxt,
productName,
issuerName
from sf_product
where rrsId = $rrs
go
EOF

To capture output from a command in shell code, surround it with backticks (`)
egs:

somevar=`my-big-command some params`
line1=`echo "$somevar" | head -1`
line2=`echo "$somevar" | head -2 | tail -1`
...