use Fcntl;   # For O_RDWR, O_CREAT, etc.
        use SDBM_File;

        tie(%h, 'SDBM_File', 'filename', O_RDWR|O_CREAT, 0666)
          or die "Couldn't tie SDBM file 'filename': $!; aborting";

        # Now read and change the hash
        $h{count} += 1;
        print $h{count};
        ...

        untie %h;

##</code><code>##

        $h{user} = "bob";

##</code><code>##

        $h{prefs} = { color => 'red', font => 'large' };

##</code><code>##

server:  foo
database: stuff

table: users
|name|age|sex|location|
|bob|12|M|Nuke York|
|mary|22|F|Lost Angles|

table: prefs
|name|color|font|
|bob|blue|large|
|mary|blue|tiny|


##</code><code>##

  SELECT name FROM prefs WHERE font = 'tiny';
|name|
|mary|

  SELECT name, color, sex FROM users, prefs
  WHERE color = 'blue';
|name|color|sex|
|bob|blue|M|
|mary|blue|F|


##</code><code>##

  $result => [
    {
      name => 'bob',
      color => 'blue',
      sex => 'M'
    },
    {
      name => 'mary',
      color => 'blue',
      sex => 'F'
    }
];