Transcript Data validation

DAY 20:
ACCESS CHAPTER 5
Tazin Afrin
[email protected]
October 29, 2013
1
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
• 1st November
– Homework 4 due
• 4th November
– MyITLab Lesson D due
• 8th November
– Homework 5 due
• 12th November
– Exam 2 on MS Access
12
THANK YOU
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