fld is any numeric, formula, memo, or BLOB field in the report.
Evaluates the field specified in the previous record and returns TRUE if the field contains a null value.
You can use this function to test for the first item in a list and to take some action when that first item is identified.
The following example is applicable to Crystal syntax:
If PreviousIsNull ({employee.EMPLOYEE ID}) Then
In an employee database with no null values in the Employee ID field, flags the first employee on the list.
Some databases support null data values and others do not. This function will not work if the active database(s) do not support null values. If the database(s) do support null values, the function can be used to reference the null values that get created as the result of a failed lookup while joining.
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