Parameters support many more features than those
mentioned here. For a complete list of features, see the
ParameterField
class.
Multiple or single value parameters
If a parameter supports multiple values, a user can
select more than one value for a parameter when the report is refreshed. If a
parameter supports single values, a user can only select one value for a
parameter when the report is refreshed. If a parameter supports multiple
values, it effectively changes from a single variable to an array that contains
many values.
Discrete or ranged parameter values
Discrete parameter values represent a singular
value, such as 1, "Jill", 3.141 or True. Ranged values represent a particular
span of values from one point to another, such as [1..45], (4..6],
["Monday","Thursday"]. The lower bound value of the range must be smaller than
the upper bound.
In addition, parameters can be both discrete and
ranged if the parameter supports multiple values.
Default values
You can specify default values for a parameter and
force the user to select one or many of them. You can also supply default
parameter values but allow the user to enter custom values. The default values
are stored in the
DefaultValues
property of the
ParameterField
Object. Once the user has selected a set of values for the report's parameters,
those values are stored in the
CurrentValues
property.
Note: Default values can only be
discrete.
Optional parameter values
If a parameter value is set to optional, users are
not forced to enter a value when prompted.
Static or dynamic parameter values
Static parameter values are stored in the report.
Dynamic parameter values are retrieved from a data source outside of the
report.
Dynamic cascading parameters values
A dynamic prompt can include a cascading list of
values that will lead the userthrough a sequence of dynamic prompts to
determine a final parameter value. For example, users might first be prompted
to pick a country before the choices for region appear.
Interactive parameter values
Parameter values can be manipulated at runtime
using the
CrystalReportViewer.ViewTimeSelectionFormula
property. The view time selection formula is applied after the results of
selection formulas saved with the report have been applied.
Types of parameter values
A parameter field must contain a certain
ParameterFieldType.
A parameter value must be one of the following
parameter types: