DAY 20: ACCESS CHAPTER 5 Tazin Afrin October 29,

OBJECTIVES Establish data validation Create input mask Create and modify lookup table 2

DATA VALIDATION Data validation is a set of constraints or rules that help control how data is entered into a field. Access provides some data validation automatically 3

DATA VALIDATION METHODS Required –Sets the Required property of a field to force data entry, such as a last name. Default value –Specifies a value that is automatically entered into a field. Validation rule –Limits the type of data a user can enter into a field. Validation text –Provides the error message telling users what they did wrong and gives them instructions on what they need to do to fix it. 4

DATA VALIDATION METHODS Input mask –Forces to conform to a specific data entry format. Lookup lists –Field values are limited to a predefined list of values. Multiple value field –Accepts multiple values in a single field. –For example, an employee might have a status of both full time and temporary. 5

REQUIRED Cannot be left blank when you create a new record. Primary keys are required fields by definition. Default Required setting is No for all the remaining fields. –Set the Required property to Yes for critical fields. –Set in design view of table. 6

DEFAULT VALUE When a majority of new records contain a common value, you can set a default value for that field to reduce data entry time. Establish a field’s default property by selecting the field in the table design view. You can type Date() in the Default Value property to insert the current date when a new record is added. –This type of default value is useful for fields like Date of Entry, Date Record Added, and Order Date. 7

VALIDATION RULE A validation rule is designed to restrict the data values that can be entered into a field. Data values that do not conform are rejected. Examples: –If all of your school’s course numbers are larger than 100, then you could establish a validation rule to prohibit values less than or equal to 100 on a registration form. Validation rules do not make the field required 8

VALIDATION TEXT Validation text informs users that the validation rule has been broken, and how to correct it. If you violate a validation rule, Access will not let you continue until the data value conforms to the rule. For example, the validation text for the rule violation above might be, “You have entered an invalid course number. Please recheck the number and enter a value greater than 100.” 9

INPUT MASK An input mask restricts the data being input into a field by specifying the exact format of the data entry. Examples: –Phone numbers –Social Security numbers –Zip codes –Dates Use input mask wizard. 10

LOOKUP FIELD A lookup field provides the user with a finite list of values to choose from. For example, class status in a university’s student table would be Freshman, Sophomore, Junior, Senior, Graduate, or Other. Use lookup wizard in design view. 11

UPCOMING DEADLINES 1 st November –Homework 4 due 4 th November –MyITLab Lesson D due 8 th November –Homework 5 due 12 th November –Exam 2 on MS Access 12

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