So far, the reports you have created have returned all the records from your database. Sometimes this is appropriate, but often reports need to filter the data based on specified criteria. This is most relevant when you're working with large databases in which there can easily be hundreds of thousands of records returned from a query, especially when joins are applied.
As with many features in Crystal Reports, there are multiple ways to filter data:
Using the Select Expert— This simple method provides a visual way to specify filtering.
Using the Record Selection Formula— This more granular, yet powerful, method involves creating a custom formula language expression to determine the filter criteria.