Page 267 - IT 402 v2.0 class 10
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DATA VALIDATION
At the time of feeding data, sometimes users may feed a wrong
information and a perfect report may not be produced. The errors in
a database may occur due to incorrect entry of data into the fields or
even due to the fields which are left blank at the time of data entry.
For example suppose in the table named Student under the field
oll No a user enters roll number with negative value which is not
acceptable as it is not valid in normal conditions. It means while
feeding information, there should be some kind of measures or
checks or filtration of input data.
In this section, we will discuss how to overcome common errors by
applying certain checking measures. In order to avoid errors in a
MS proper checking of data or some predefined control condition is re uired.
For example, if a condition is applied that minimum fee for any course in a college is `1500/- and if a student
pays a fee amount equal to `1400/-, then it should not be acceptable.
ata alidation ensures that the data being entered in the table is correct and valid by applying some
conditions in the particular entry of field.
In other words it can be said that validation involves checking of data against some user-defined conditions
and it allows entry of only that data which satisfies the defined conditions.
In database package there are different ways to control the entry of data into a table. et us discuss about
the different ways to control the entry of data in detail:
FIELD LEVEL VALIDATION
Field level data validation ensures that the data entered in a particular field is correct and valid. It checks the
correctness of entries in a particular field on which validation condition has been applied.
For example suppose a condition is applied on a field while designing the table that the name of the customer
should not be left blank, then if the user tries to save the record with blank customer name, then this validation
check does not allow the user to do so.
In ase the field level validation is applied by setting some special properties to the individual fields.
database administrator can apply more than one validation check on a single field. he following properties
can be applied for field level validation in a particular field of the table:
ntry e uired
ength
Default Value
Entry Required
ntry re uired property is applied to ensure that the field is not left blank while saving the record in a table. If
the user leaves the field blank and tries to save the record an error message will be displayed and the record
will not be saved. he default value of ntry re uired is No to set it to es click on the option list box and
select the es option. ntry re uired option cannot be applied if the field is set as rimary ey .
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