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Working with the Lookup Feature
Using the Lookup Wizard, you can instruct a field to look up its values in another table or query or from a fixed list of values. You can also display the list of valid values in a combo or list box. A lookup is generally created from the foreign key (the "many" side) to the primary key (the "one" side) of a one-to-many relationship.You can invoke the Lookup Wizard by selecting Lookup Wizard from the list of data types for the field. The first wizard dialog box asks whether you want to look up the values in a table or query or whether you want to input the values. I recommend that you always look up the values in a table or query; this makes your application easier to maintain. The second dialog box asks you to indicate the table or query used to look up the values. Select a table or query and click Next to open the third dialog box. This step of the Lookup Wizard asks you which field in the table or query will be used for the lookup. The fourth step of the Lookup Wizard asks you the sort order you want for your list. The fifth step, shown in Figure 2.21, gives you the opportunity to control the width of the columns in your combo or list box.
Figure 2.21. In the fifth step of the Lookup Wizard, you can adjust the column widths.
Chapter 5, "What Every Developer Needs to Know About Forms." You can modify the SQL statement for the combo box later, if necessary.
Figure 2.22. The field properties set by the Lookup Wizard.
NOTEIn my opinion, the lookup feature is more of a hindrance than a help. After you invoke the lookup feature, you and your users will no longer have easy access to the underlying numeric values stored in the foreign key field. You will see only the lookup value displayed in the combo box. This makes troubleshooting application problems very difficult.The main advantage of the lookup feature is that it facilitates the process of building forms by automatically adding a combo box to a form whenever a field with a lookup is placed on a form. Personally, I find it so easy to build a combo box on a form that I do not find the lookup feature to be much of a timesaver. After evaluating the pros and cons of this user-related feature, I opted to eliminate it from the applications that I build.
