The Table
Modes button offers us several presentation options. We can choose a
minimal level of detail using the Name Only option, or successively add
more detail until reaching the Column Properties view, which presents
names of the tables selected, plus field names and properties, as well.
Let's
select the highest level of detail, since our diagram is intended to support
the creation of a data dictionary.
7.
Ensure that no
one table is already selected (you can simple click any point in the "white
space" of the diagram design surface, to deselect any tables).
8.
Select Edit
--> Select All from the main menu.
All
tables become highlighted / selected.
9.
Click the Table
Modes button.
10.
Click Column
Properties from the expanded button.
The
tables in the diagram shift to the most detailed of the view options, showing table
name, and field names and properties, as partially depicted
in Illustration 12.
Illustration 12: We
Shift to Column Properties Mode (Partial View)
The Column
Property mode makes clear the need to be able to rearrange the tables for
the sake of clarity. All we need do is click on a given table and drag it into
position so that its joins are clear. We can use the Zoom feature (the
expanded button appears in Illustration 13) as a tool in this process,
as well as from the perspective of the final presentation.
Illustration 13: The Expanded
Zoom Modes Button
11.
Click the Sales
table to select it.
12.
Drag the table
to the right, well away from the other tables, to distinguish it.
13.
Click the Zoom
Modes button to expand it.
14.
Select 50%
within the menu that appears.
The
table appears, in reduced mode, as shown in Illustration 14.
Illustration 14: The Expanded
Zoom Modes Button
We can
use the standard key combinations to select multiple tables (CTRL-click
and SHIFT-click), as well as "lassoing" our selections with
the mouse, much as we can do in many Windows-based graphical applications. We
can add further tables (not already in the diagram) by clicking the Add
Table button, which resurrects the Add Table dialog that we have
already encountered. We can also hide tables through the use of the Hide
Table button. Hide Table allows us to remove a given table from the
diagram without actually deleting it from the database (altering the database
from the diagram is possible, assuming the appropriate user privileges - always
exercise care with regard to unintentional modification).
The Add
Table and Hide Table buttons appear as depicted, left to right,
respectively, in Illustration 15.
Illustration 15: Add
Table and Hide Table Buttons, Left to Right, Respectively
In the
case of the simple pubs database, the database diagram has
already managed the joins for us. Let's take a look behind the scenes to see
how joins are put in place, for those times down the road when the diagram will
not be able to conclude that a join is appropriate (say we have two fields that
should be joined, but which have different names entirely.)
We can
see readily that the Titles table joins several other tables, and so we
will use it as an example in our exploration of the information behind the
joins.
15.
Right-click
the Titles table.
16.
Select
Properties from the context menu that appears, as shown in Illustration
16.
Illustration 16: Right-Click
and Select Properties for the Titles Table ...
The Properties
dialog appears.
17.
Select the Relationships
tab.
The Relationship
information for our example appears, as depicted in Illustration 17.
Illustration 17: The
Details behind the Join ...
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