Excel's Formula - sisman

Chapter 19: Conditional Formatting and Data Validation 545
In many cases, you can simply take advantage of Excel’s data validation feature, which is
described next.
Data Validation
Excel’s data validation feature is similar in many respects to the conditional formatting feature.
This feature enables you to set up certain rules that dictate what you can enter into a cell. For
example, you may want to limit data entry to whole numbers between 1 and 12. If the user makes
an invalid entry, you can display a custom message, such as the one shown in Figure 19-25.
Figure 19-25: Displaying a message when the user makes an invalid entry.
As with the conditional formatting feature, you can use a logical formula to specify your data validation
criteria.
The data validation suffers from a potentially serious problem: If the user copies a cell
that does not use data validation and pastes it to a cell that does use data validation,
the data validation rules are deleted. In other words, the cell then accepts any type of
data.
Specifying validation criteria
To specify the type of data allowable in a cell or range, follow these steps:
1. Select the cell or range.
2. Choose Data➜Data Tools➜Data Validation.
Excel displays its Data Validation dialog box.
3. Click the Settings tab (see Figure 19-26).