Queries are very productive tools inside
Map 3D. We can use these to Reference or Create Data from one
file to another. This will allow us pull info needed for a
current project from other sources. With this tool we can
extract data in many different ways. In fact, we can extract
anything from specific object data to which layer the
information resides on, or both. The software also allows us to
pull it in as a preview or draw the data directly into our new
drawing. So as we can all see, this can be helpful in many
different types of situations. In this article we will look at
pulling in data based on location and property value
simultaneously. This it what is known as a compound query and
will let us get pretty specific about what we want to see in our
drawing.
In this process the first thing to do is to get the drawings we
will be pulling data from and attach those to our current
drawing as source drawings. These must be attached in order to
create a path the computer can use. We can do this by clicking
Data in the map explorer and choosing to attach the source
drawing. At this point we can browse through our aliases
(designated directories) and find the one that contains the
drawings we are searching for.


At this point we simply choose the drawings
within the folder we want to reference and choose “add.”
Once the drawings are added in the map explorer we are free to
retrieve data from those sources.

From the screenshot above you should be
able to see that we have four different types of queries to
choose from. Location type allows us to choose a physical
location to pull data from on the map. Property lets us pull
objects by an AutoCAD property such as layer or linetype. Data
query type has us pulling info by Attributes or Object Data,
etc. Finally the SQL type requires us to pull from an external
database, like a Microsoft Database file (.mdb) for example. As
I wrote before, in our query we want to retrieve the land value
in a specified location on the map. The first thing we are going
to do is execute a preview query of all the parcels to see where
they are located.

In order to get the parcels in, we need to
choose “property” as our query type. This will let us select
which AutoCAD property we want and give us access to the AutoCAD
layers in all of the attached drawings. Here we can choose to
get our parcels layer in which all the parcels reside.

Once we OK the parcels layer, we are taken
back to the query definition dialogue box where we can execute
the query in preview mode to see our parcels without actually
creating objects in our drawing.

Now we can see the parcels, but when
executing the query in preview mode it acts a lot like an xref.
Now we will be able to clear our current query and begin a new
one that will give us what we want.
When we begin our new query we will simply clear the previewed
one and select location as our new query type. Then it will ask
us how we want to define the location. We will have many options
on how to do that in the dialogue box you see below.

In this case we are going to choose a
polygon to enclose the north side of town.

Once we have the location specified we will
make sure that the And modifier is chosen in the query type box.
We will now choose the data we wish to retrieve by clicking
Data.

When we click the Data option we will go to
the Parcels table and choose to get Land_Value section of the
object data. We can choose a modifier of equal to, less than,
greater than and so on. We will choose “greater than” in the
amount of 1,000,000.

As you can see, our query is now more
defined and will give us exactly what we are looking for. We can
define our query as specifically as we want, and the “and”
modifier will allow us to add as many parameters as we need.
Once we execute the query we just designed in draw mode, we will
get every parcel in the specific location we designated in
excess of $1,000,000 in value, as you can see in the picture
below.

In Map 3D 2008 Queries can help us pull very specific data from
drawings very quickly, as opposed to sorting through them
basically by hand. This allows us to make display maps
pertaining to specific areas quickly and allows us to export
this data also if need be. It can be a big time saver and is
pretty neat to see exactly how specific you can get with it.