Managing the Consistency, Format, and Integrity of Your Data 105 For more information: · See the Microsoft Access 2003 online training "Take the Controls," available through Microsoft Office On- line. You can also refer to the articles related to tables under the topic "Creating and Working with Data- bases and Objects" in the Microsoft Office Access 2003 Assistance, available through Microsoft Office Online. Chapter Summary In this chapter, you learned more about the use of table relationships, especially how Access uses referential integrity to maintain relationships between records. The options for cascading updates and cascading deletions can be used with referential integrity to make maintaining your database easier. You learned more about table and field properties, including how the size of a field can affect the performance of your database and how to create indexes for fields and combinations of fields that you'll use in searches and for sorting records. Finally, you learned how to use three important field properties to help keep data accurate and consistentthe Input Mask property, the Format prop- erty, and the Validation Rule property. With the conclusion of this chapter, we've come a long way in setting up tables that we'll use throughout the remainder of this book. In the next chapter, you'll learn how you can import data that's stored in spreadsheets, text files, and other formats into tables in an Access database. Testing validation rules Creating a validation rule for a table or a field that already contains data might make some of the data invalid. You can test a validation rule by right-clicking the title bar of the Table Design window and then clicking Test Validation Rules. In addition to testing validation rules for the table and for fields, this command tests whether the table's data conforms to the settings you've entered for the Required property and the Allow Zero Length property. Q&A Q1: A1: I'd like to see more than one column in a lookup field. Is that pos- sible? Yes. Open the table with the lookup field in Design view, click in the field, and then click the Lookup tab in the Field Properties area. Change the Column Count property to the number of columns you want. You might also need to adjust the Column Widths property. If one column's width is 0 ", enter a positive number to view the data in that column. I have a lot of numbers to format. Can I enter an expression in the Format property to show negative numbers in a different color? You could use a combination of special characters to do this. The following expression would show positive numbers in green and negative numbers in red, enclosed in parentheses (with blank fields displaying Zero or Unknown ). #,##0.00[Green];(#,##0.00)[Red];"Zero" "Unknown" Q2: A2: Q3: Is there an easy way to let the users of my database know about a validation rule before they enter data?