MS Access for the Business Environment: MS Access as a Documentation Tool: Database Diagramming - Page 4
August 2, 2004
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.
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.
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.
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.
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.
The Properties dialog appears.
17. Select the Relationships tab.
The Relationship information for our example appears, as depicted in Illustration 17.