#!/bin/sh
# Quote everything,
tr , "\t" |
sed 's/\t\([^"\t]\+\)/\t"\1"/g' |
sed 's/\([^"\t]\+\)\t/"\1"\t/g' |
# replace empty with null,
sed 's/\t\t/\tnull\t/g' |
sed 's/\t\t/\tnull\t/g' |
sed 's/\t$/\tnull/g' |
sed 's/^\t/null\t/g' |
tr "\t" , |
# and add parens around each line
sed 's/^/(/g' | sed 's/$/),/g'