mulzal

$ cat file.txt
('data1','bigdata245','useful1','dateofday','useful2','trash44',NULL)
('data1','bigdata245','useful1','dateofday','useful2','trash44',NULL)
('data1','bigdata245','useful1','dateofday','useful2','trash44',NULL)
$ while read; do echo $REPLY|awk -F "," '{print $3","$5}'; done<file.txt
'useful1','useful2'
'useful1','useful2'
'useful1','useful2'