588 Part III Working with Data

Figure 20-23: Use the Link Select dialog box to create combined selection sets of objects from queries and/or direct selection in your drawing.

3.Click Execute to add the query or selection of objects in your drawing to the Link Select operation.

4.Create a second selection set using the same process.

5.From the Do drop-down list, choose one of the logical operators. You now have one selection set from the combined selection sets you specified.

6.If you want, you can now create an additional selection set and use an operator to combine it with the previous selection set created in Step 5.

7.Choose Finish to complete the process.

Working with Query Files

You can store, edit, rename, and delete queries. You can also import and export them for use by others. To use ASE links created in Releases 13 and 14, you need to convert them to AutoCAD 2005 format.

Storing queries

As I discussed previously, you can store a query by clicking Store on any tab. Stored queries are displayed under the drawing in the dbConnect window. To execute a stored query, choose dbConnect Queries Execute Query. Choose the query you want to execute and click OK. It helps if the queries have names that meaningfully relate to the query.

You can also edit a query. Choose dbConnect Queries Edit Query. Choose the query and click Continue. In the Query Editor, make the desired changes and choose Store.

Chapter 20 Working with External Databases

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To rename a query, click it in the dbConnect window. Click it again to display an edit box. You can now edit the query’s name. Remember that you have to name the query up front. If you’re not sure what the query will consist of, use the default name, construct your query, and then rename it to something more meaningful afterward.

To delete a query, choose dbConnect Queries Delete Query. Choose the query or queries and click OK.

Importing and exporting queries

To export a query that has been saved (by clicking Store in the Query Editor), choose dbConnect Queries Export Query Set. In the Export Query Set dialog box, navigate to the desired folder and choose a name. Click Save. Queries have a .dbq filename extension.

Note	To find the location of your queries, choose Tools Options and click the Files tab. Double-
	click Data Sources Location to see the path.

To import a query that has been exported and named, choose dbConnect Queries Import Query Set. You need to know the name and location of the .dbq file. In the Import Query Set dialog box, locate the file and click Open. If your drawing already contains a query with the same name, AutoCAD adds a number to the name of the query so it has a unique name. This can easily occur because AutoCAD assigns default names to queries.

Summary

Using external databases to store data about drawing objects can reduce the size of drawings, simplify reporting, make data accessible to all users on a network, and enable you to edit a database from inside AutoCAD. In this chapter you read about:

Configuring a data source

Connecting a database table with your drawing

Creating a link template

Creating links between drawing objects and rows in the database

Creating labels containing information from the database

Defining SQL queries to select and sort the data you view

Selecting objects based on queries

Storing and saving queries

Converting links from Releases 12 through 14.

This chapter ends Part III, “Working with Data.” In Part IV, you start to draw in three dimensions. In the next chapter, I discuss how to specify 3D coordinates.

Drawing in Three

Dimensions

Part IV introduces you to three-dimensional drawing. AutoCAD creates three types of 3D objects, also called models — wireframes, surfaces, and solids. Wireframes, as the name implies, look like models created with wire. They don’t have real surfaces

or solidity. However, they’re useful for creating shapes that you can turn into surfaces or solids. Surfaces, unlike wireframes, can hide objects behind them. They’re especially useful for creating unusually shaped objects. Solids are defined as the entire volume of space they enclose. You can add and subtract solids from each other, creating realistic objects.

AutoCAD LT can only create wireframes and one kind of surface. AutoCAD LT’s 3D capabilities are quite limited, but you can still create simple 3D objects in AutoCAD LT. Furthermore, AutoCAD LT can open and display a drawing that contains 3D objects created in AutoCAD.

In Chapter 21, I explain the basics of 3D drawing, including specifying 3D coordinates, using the User Coordinate System for 3D drawing, and creating objects with elevation and thickness. Chapter 22 explains the techniques for viewing 3D objects. Chapter 23 covers surface models. Chapter 24 explains how to create true solids and covers editing in three dimensions. Chapter 25 explains how to create photorealistic views of your 3D drawings using AutoCAD’s rendering feature.

Note	Chapters 23 through 25 apply to AutoCAD only.

P A R T

IV

In This Part

Chapter 21

Specifying 3D

Coordinates

Chapter 22

Viewing 3D Drawings

Chapter 23

Creating 3D Surfaces

Chapter 24

Creating Solids

and Editing in 3D

Chapter 25

Rendering in 3D

Specifying 3D

Coordinates

Until now, you’ve worked with two axes, X and Y. When you work in three dimensions, you add the Z axis. After you have a drawing with 3D objects, you can view it from any angle. The view you’ve

been using in 2D drawings is like looking at a house from the top, which you could call a plan view or a floor plan. From this view, even a 3D drawing looks two-dimensional. But when you look at a 3D drawing from an angle, you can see that there’s more to it than meets the eye. Figure 21-1 shows the plan view of an office building. Figure 21-2 shows the same drawing viewed in a perspective view from the front.

Figure 21-1: An office building in plan view.

Thanks to Roger Cusson of Interface Architectural

Software, Montreal, Quebec, for this drawing.

Although this drawing is quite complex, you can easily get started by working on simpler models. Three-dimensional drawing is not as difficult as it seems at first. In this chapter, I start by explaining how to work with 3D coordinates. I also cover wireframe models and 3D surfaces created with thickness and elevation. These are essentially 2D objects placed in 3D space and are, therefore, a good place to start when learning about drawing in 3D. Most of the features that I cover in this chapter apply to AutoCAD LT as well as AutoCAD.

21C H A P T E R

In This Chapter

Understanding 3D drawings

Working with 3D coordinates

Using point filters, object snaps, and grips in 3D

Using elevation and thickness

Creating a custom UCS for 3D drawings