how can I use sed to replace blank fields in a csv file

how can I use sed to replace blank fields in a csv file

References

Reference NO 1

http://stackoverflow.com/questions/13656215/how-can-i-use-sed-to-replace-blank-fields-in-a-csv-file-with-a-string

Reference NO 2

http://stackoverflow.com/questions/5688231/how-to-replace-null-valuefield-with-word-on-csv-file

Reference NO 3

http://unix.stackexchange.com/questions/26941/how-to-manipulate-a-csv-file-with-sed-or-awk

Reference NO 4

http://sed.sourceforge.net/sedfaq4.html

Reference NO 5

http://askubuntu.com/questions/235723/how-do-you-use-sed-to-edit-a-csv-file

Reference NO 6

http://www.webforefront.com/bigdata/xsvfiles.html

Reference NO 7

http://soft.zoneo.net/Linux/remove_empty_lines.php

Reference NO 8

http://superuser.com/questions/567278/can-i-use-a-batch-file-to-remove-blank-columns-in-a-csv