Here is the setup procedure for creating a dynamic query from a relational database directly into Google Earth (following view-based refresh directions posted at http://code.google.com/apis/kml/documentation/kml_tut.html#network_links).

 The following two files are all that is needed to provide the capability viewable at http://dods.mbari.org/uwcd/viewUWCD.kml

1. Create a "master" .kml file with the refresh parameters and a network link to the .cgi file:

   > pwd
   /var/www/dods_html/uwcd
   <187 elvis.shore.mbari.org /dods_html/uwcd> cat viewUWCD.kml
   <?xml version="1.0" encoding="UTF-8"?>
   <kml xmlns="http://earth.google.com/kml/2.2"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://earth.google.com/kml/2.2
       http://code.google.com/apis/kml/schema/kml22beta.xsd">
   
     <Folder>
       <name>MBARI Upper Water Column Data</name>
       <visibility>0</visibility>
       <open>0</open>
       <description>Check boxes to see data in your view.
       Queries begin 2 seconds after you stop navigating.</description>
       <NetworkLink>
         <name>BOG Bottle Data</name>
         <visibility>0</visibility>
         <open>0</open>
         <description>Query for Bottle Data</description>
         <refreshVisibility>0</refreshVisibility>
         <flyToView>0</flyToView>
   
         <Link>
           <href>http://elvis.shore.mbari.org/cgi-bin/bogKML.cgi</href>
           <refreshInterval>2</refreshInterval>
           <viewRefreshMode>onStop</viewRefreshMode>
           <viewRefreshTime>1</viewRefreshTime>
           <viewBoundScale>0.75</viewBoundScale>
         </Link>
       </NetworkLink>
   
   
     </Folder>
   </kml>

2. Create the .cgi file with the spatially constrained query and KML output:

   > pwd
   /var/www/cgi-bin
   <195 elvis.shore.mbari.org /www/cgi-bin> cat bogKML.cgi
   #!/usr/bin/perl
   
   # Script to query BOG Bottle data from Google Earth
   #
   # Mike McCann  16 april 20009
   # MBARI
   
   use DBI;
   
   #
   # Debugging stuff:  All debugging print statements are commented out with
   # '##'.  Must turn on text/html to see the debugging output, should you
   # need to do that.
   #
   ##print "Content-type: text/html\r\n\r\n";
   ##print "Hello, World.";
   
   ##print "String = $ENV{'QUERY_STRING'}\n\n<p>";
   @values = split(/&/, $ENV{'QUERY_STRING'});
   my %qVars = ();
   foreach $i (@values) {
           ($varname, $mydata) = split(/=/, $i);
           $qVars{lc $varname} = $mydata;
           ##print "The value of $varname is $mydata\n\n<p>";
   }
   
   #
   # Get parameters from Query String.  GE will provide bbox.  qsql is for
   # potential future use.
   #
   
   $bbox = $qVars{'bbox'};
   $qsql = $qVars{'qsql'};
   
   ##print "bbox = $bbox\n";
   
   if ( $bbox ) {
                   ($west, $south, $east, $north) = split(',', $bbox);
   }
   elsif ( $qsql ) {
                   # Use this SQL for the query below
   }
   else {  # Some default bounding box - for testing
                   ($west, $south, $east, $north) = (-124, 35.2, -122, 36);
   }
   
   #
   # Set up database connection (replace <...> entries with actual connection parameters)
   #
   ##print "\nConnecting to the Database<br>";
   my $dbh = DBI->connect("DBI:Sybase:server=<db_server>", "<ro_login>", "<ro_password>", {PrintError => 1});
   $dbh->do("use BOG");
   
   #
   # Count the records for the query and set up the stride for subsampling
   # - careful that we use the same join and where clause as we do below...
   #
   my $countSQL = <<EOS;
   SELECT     count(*)
   FROM       dbo.BCTD INNER JOIN
                 dbo.EXPEDITION ON dbo.BCTD.EXPD = dbo.EXPEDITION.expd
   WHERE     (dbo.EXPEDITION.dec_lat > $south) AND (dbo.EXPEDITION.dec_lat < $north) AND
             (dbo.EXPEDITION.dec_long > $west) AND (dbo.EXPEDITION.dec_long < $east)
   EOS
   
   ##print "\nExecuting countSQL: $countSQL";
   my $sth = $dbh->prepare($countSQL);
   $sth->execute;
   while ( my $rrow = $sth->fetchrow_arrayref() ) {
           $numRows = $$rrow[0];
   }
   ##print "<br>numRows = $numRows\n";
   $bottlesToDisplay = 500;
   $stride = int($numRows / $bottlesToDisplay);
   $stride = 1 if $stride < 1;
   ##print "<br>stride = $stride\n";
   
   
   
   #
   # Construct SQL statements with DateTime given in ISO8601 format.  If SQL passed in then
   # construct that query with the additional ISO8601 date format.  Apply the stride from above.
   #
   my $sql;
   if ( $qsql ) {          # Add DateTime and put in some newlines for cleaner display in the description
                   # Need to add ISO date time to SELECT
                   $qsql =~ s/FROM/, rtrim(convert(char, CollectionEventDTG,126)) + 'Z' as DateTime \nFROM/;
                   $qsql =~ s/WHERE/\nWHERE/;
                   $qsql =~ s/ORDER/\nORDER/;
                   $sql = $qsql;
   }
   else {
   ##SELECT     dbo.EXPEDITION.dec_lat AS Latitude, dbo.EXPEDITION.dec_long AS Longitude,
   ##           dbo.BCTD.BOTTLE, dbo.EXPEDITION.cruise, dbo.BCTD.DEPTH, dbo.BCTD.CTRB_ID,
                   $sql = <<EOS;
   SELECT     *,
              rtrim(convert(char, dbo.EXPEDITION.date_time,126)) + 'Z' as DateTime
   FROM       dbo.BCTD INNER JOIN
                 dbo.EXPEDITION ON dbo.BCTD.EXPD = dbo.EXPEDITION.expd
   WHERE     (dbo.EXPEDITION.dec_lat > $south) AND (dbo.EXPEDITION.dec_lat < $north) AND
             (dbo.EXPEDITION.dec_long > $west) AND (dbo.EXPEDITION.dec_long < $east) AND
             BCTD.CTD_BOTTLE_ID % $stride = 1
   ORDER BY  dbo.EXPEDITION.date_time
   EOS
   
   }
   
   
   #
   # Execute the SQL, and build the placemarks
   #
   ##print "\nExecuting sql: $sql";
   $sth = $dbh->prepare($sql);
   $sth->execute;
   
   my $placemarks = '';
   my $count = 0;
   while ( my $rrow = $sth->fetchrow_hashref() ) {
           ##foreach my $k ( keys %$rrow ) {
                   ##print "k = $k, v = " . $$rrow{$k} . "\n";
           ##}
           ##print "\n<br>";
   
   
           $lat = $$rrow{'dec_lat'};
           $lon = $$rrow{'dec_long'};
           $depth = $$rrow{'DEPTH'};
   
           unless ($lat && $lon && $depth) {
                           next;
           }
   
           $isodate = $$rrow{'DateTime'};
           $bottle = $$rrow{'BOTTLE'};
           $cruise = $$rrow{'cruise'};
   
           $name = "$cruise $bottle";
   
           $placemarks .= "<Placemark>\n<name>$name</name>\n";
           $placemarks .= "<TimeStamp>\n<when>$isodate</when>\n</TimeStamp>\n";
           $placemarks .= "<description><![CDATA[";
           $placemarks .= "<div>$name</div><br><br>\n";
           foreach my $k ( sort keys %$rrow ) {
                   $placemarks .= "<div><b>$k:</b> " . $$rrow{$k} . "</div>\n";
           }
           $placemarks .= "]]></description>\n";
           $placemarks .= "<styleUrl>#square_pair</styleUrl>\n";
           $placemarks .= "<Point>\n<altitudeMode>absolute</altitudeMode>\n";
           $placemarks .= "<coordinates>$lon,$lat,-${depth}</coordinates>\n</Point>\n";
           $placemarks .= "</Placemark>\n";
   
           $count++;
   
   }
   $dbh->disconnect;
   
   
   #
   # Build up KML and deliver it to the client
   #
   my $kml = <<EOK;
   <?xml version="1.0" encoding="UTF-8"?>
   <kml xmlns="http://earth.google.com/kml/2.1"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://earth.google.com/kml/2.1
       http://code.google.com/apis/kml/schema/kml21.xsd">
   
   
   <Folder>
   EOK
           if ( $qsql ) {
                   $kml .= "<name>BOG DB Bottle Query</name>\n";
           }
           else {
                   $kml .= "<name>Bottles</name>\n";
           }
   
           $kml .= <<EOK;
   <Document>
   <name>Individual Bottles</name>
           <Style id="sn_square_copy29">
                   <IconStyle>
                           <color>ffffff00</color>
                           <scale>0.5</scale>
                           <Icon>
                                   <href>http://maps.google.com/mapfiles/kml/shapes/square.png</href>
                           </Icon>
                   </IconStyle>
                   <LabelStyle>
                           <scale>0.7</scale>
                   </LabelStyle>
           </Style>
           <Style id="sh_square_copy13">
                   <IconStyle>
                           <color>ffffff00</color>
                           <scale>0.66</scale>
                           <Icon>
                                   <href>http://maps.google.com/mapfiles/kml/shapes/square.png</href>
                           </Icon>
                   </IconStyle>
                   <LabelStyle>
                           <scale>0.77</scale>
                   </LabelStyle>
                   <BalloonStyle>
                     <bgColor>ffffffff</bgColor>
                     <textColor>ff000000</textColor>
                     <text>\$[description]</text>
                     <displayMode>default</displayMode>
                   </BalloonStyle>
           </Style>
           <StyleMap id="square_pair">
                   <Pair>
                           <key>normal</key>
                           <styleUrl>#sn_square_copy29</styleUrl>
                   </Pair>
                   <Pair>
                           <key>highlight</key>
                           <styleUrl>#sh_square_copy13</styleUrl>
                   </Pair>
           </StyleMap>
   
   <visibility>0</visibility>
   <open>0</open>
   <description><![CDATA[$numRows Bottles in this view, showing every $stride<br><br><br><br>Resulting from query<br><pre>$sql</pre>]]></description>
   $placemarks
   </Document>
   </Folder>
   </kml>
   EOK
   
   print "Content-type: application/vnd.google-earth.kml+xml\r\n\r\n";
   print $kml;