Report fields represent the only way to map data from the data source into
the report generating routines. When the data source of the report is a ResultSet,
all fields must map to corresponding columns in the ResultSet
object. That is, they must have the same name as the columns they map and a
compatible type.
For example:
If we want to generate a
report using data retrieved from the table Employees, which has the
following structure:
Column Name Datatype Length--------------------------------------
EmployeeID int 4
LastName varchar 20
FirstName varchar 10
HireDate datetime 8
we can define the
following fields in our report design:
<field name="EmployeeID" class="java.lang.Integer"/> <field name="LastName" class="java.lang.String"/><field name="FirstName" class="java.lang.String"/>
<field name="HireDate" class="java.util.Date"/>
If we declare a field that
does not have a corresponding column in the
ResultSet,
an exception will be thrown at runtime. Columns present in the ResultSet
object that do not have corresponding fields in the report design do not
affect the report filling operations, but they also wont be accessible.