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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