How do i jump back to the previous read if left empty - bash

Question

Default_Dir=/export/home/cwatts/test
Default_Log=DB.Audit
echo "Please, enter your Fullname [ENTER]:"
read fname
if [ -z "$fname" ]; then
echo "Please enter a value!"
exit 0
else
echo "Please, enter the Database name [ENTER]:"
read dbname
if [ -z "$dbname" ]; then
echo "Please enter a value!"
else
echo "Please, enter a brief Description [ENTER]:"
read desc
if [ -z "$desc" ]; then
echo "Please enter a value!"
fi
fi
fi
if [ ! -d $Default_Dir ]; then
echo "directory doesn't exit, it will be created"
mkdir $Default_Dir
fi
echo `date -u` $dbname $fname $desc >> $Default_Dir/$Default_Log
exit

Answer 1

You can do something like this:
while [ -z "${value-}" ]
do
echo "Please, enter your Fullname [ENTER]:"
read value
done

Answer 2

Expanding somewhat on l0b0's answer and refactoring for legibility and idiomatic expression:
nonempty () {
test -n "$1" && return 0
echo "Please enter a value" >&2
return 1
}
while true; do
read -p "Please, enter your Fullname [ENTER]: " fname
nonempty "$fname" || continue
read -p "Please, enter the Database name [ENTER]: " dbname
nonempty "$dbname" || continue
read -p "Please, enter a brief Description [ENTER]:" desc
nonempty "$desc" || continue
break
done
date -u +"%c $dbname $fname $desc" >> $Default_Dir/$Default_Log
(The hack to put the string you want to echo in the format string of date will break if any of the values could contain a percent sign.)
If you are okay with the slightly dubious practice of having a function define global variables for you, the code duplication can still be reduced significantly.
accept () {
read -p "$2 [ENTER]: " "$1"
test -n "${!1}" && return 0
echo "Please enter a value" >&2
return 1
}
while true; do
accept fname "Please, enter your Fullname" || continue
accept dbname "Please, enter the Database name" || continue
accept desc "Please, enter a brief Description" || continue
break
done
The indirect variable reference ${!var} is a Bashism, and not portable to other shells.