unable to echo value after exporting variable using getopts

Question

I'm trying to figure out in my script, why my variable dbname isn't being set when using getopts after explicitly doing an export on that variable. I tried do an echo, echo $dbname and its the only variable that doesn't have a value. Here's my code in progress:

#!/bin/bash

export SCHEMAMAIN="$dbname__source"
export OLD="/tmp/Old.out"
export NEW="/tmp/New.out"
PSQL=$(which psql)

usage () {
    echo "Usage: $0 -o oldhosts" -d dbname -t table -n newhosts""
}

while getopts ":o:d:t:n:" opt; do
  case $opt in
    o) oldhosts="$OPTARG";;
    d) export dbname=${OPTARG};;
    t) export table=${OPTARG};;
    n) newhosts="$OPTARG";;
    *) echo "Error unknown option -$OPTARG"
       usage
       exit 1
       ;;
  esac
done

if [[ $oldhosts == 'hosts1' ]]; then
    HOST="myevents-01.foobar.au-fareast-1.foobar.amazonaws.com"
   elif [[ $oldhosts == 'hosts2' ]]; then
    HOST="myevents-02.foobar.au-fareast-1.foobar.amazonaws.com"
   else
    echo "Old source hosts is incorrect:"
        exit 1
fi

if [[ $newhosts == 'hosts3' ]]; then
    HOST2="myhost-foobar-hosts-3-foobarhosts-1vjldgvvna7.foobar.au-fareast-1.foobar.amazonaws.com"
   elif [[ $newhosts == 'hosts4' ]]; then
    HOST2="myhost-foobar-hosts-4-foobarhosts-1dy7izxwwol.foobar.au-fareast-1.foobar.amazonaws.com"
   else
    echo "New hosts is incorrect:"
        exit
fi

echo "$HOST"
echo "$dbname"
echo "$SCHEMAMAIN"
echo "$table"
"$PSQL" -h "$HOST" -U masteruser -d "$dbname" -p 5439 << EOF
        \a
        \t
        \o $OLD
    SELECT column_name
    FROM information_schema.columns
    WHERE table_schema = '$SCHEMAMAIN'
    AND table_name   = '$TBL'
    order by ordinal_position;
EOF

Answer 1

What if you run the getopts loop at the top of the file and change

export SCHEMAMAIN="$dbname__source"

to

export SCHEMAMAIN="${dbname}__source"

?

Edit

@EtanReisner made a comment on it already.