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Getting Help from the Expression Builder
The Expression Builder is a helpful tool for building expressions in your queries, as well as in many other situations in Access. To invoke the Expression Builder, click in the Field cell of your query design grid and then click Build on the toolbar (see Figure 4.21). Notice that the Expression Builder is divided into three columns. The first column shows the objects in the database. After selecting an element in the left column, select the elements you want to paste from the middle and right columns.
Figure 4.21. The Expression Builder makes it easier for you to create expressions in your query.
The example in Figure 4.22 shows Functions selected in the left column. Within Functions, both user-defined and built-in functions are listed; here, the Functions object is expanded with Built-In Functions selected. In the center column, Date/Time is selected. After you select Date/Time, all the built-in date and time functions appear in the right column. If you double-click a particular functionin this case, the DatePart functionthe function and its parameters are placed in the text box at the top of the Expression Builder window. Notice that the DatePart function has four parameters: interval, date, firstweekday, and firstweek. If you know what needs to go into each of these parameters, you can simply replace the parameter place markers with your own values. If you need more information, you can invoke help on the selected function and learn more about the required parameters. In Figure 4.23, two parameters are filled in: the interval and the name of the field being evaluated. After clicking OK, the expression is placed in the Field cell of the query.
Figure 4.22. The Expression Builder with the DatePart function selected and pasted in the expression box.
Figure 4.23. A function pasted by Expression Builder with the parameters updated with appropriate values.
