echo "create table place_classtype_".pg_escape_string($aPair[0])."_".pg_escape_string($aPair[1])." as ";
echo "select place_id as place_id,st_centroid(geometry) as centroid from placex where ";
echo "class = '".pg_escape_string($aPair[0])."' and type = '".pg_escape_string($aPair[1])."';\n";
echo "create table place_classtype_".pg_escape_string($aPair[0])."_".pg_escape_string($aPair[1])." as ";
echo "select place_id as place_id,st_centroid(geometry) as centroid from placex where ";
echo "class = '".pg_escape_string($aPair[0])."' and type = '".pg_escape_string($aPair[1])."';\n";