# DataSetParam

Describes an input and/or output parameter of the data set query.

### Description

The data set parameter definition element describes the parameters of the data set query. A parameter can be input only, output only, or both.

### See Also

The Parameter Definitions section above for the rules to identify a parameter by name vs. position

## name

The name of the parameter.

### Description

The name of the parameter. Required. Must be unique within a data set definition.

### See Also

The Parameter Definitions section above for the naming rules

## position

The 1-based position of the parameter, as defined by the underlying driver.

### Description

The 1-based position of the parameter, as defined by the underlying driver. Required for data sets that identify input parameters by position instead of name. Ignored otherwise.

### See Also

## dataType

The optional data type of the parameter.

### Choices

- string: Arbitrary Unicode text.
- decimal: Any type of number including currency. Fixed decimal, arbitrary precision.
- float: A scientific amount using the usual floating point notation.
- date-time: A date, time or combination of date and time.
- integer: A whole number.

### Description

The optional data type of the parameter. Required only for data sets that require this information. Complex data set parameter data types, such as structure or table parameters of a query, are reserved for future releases, and are not listed in the Choices specification.

### See Also

## isOptional

Whether the report must provide a value for the input parameter.

### Description

If false, the report must provide a value for the input parameter. If true, the value is optional. This property value is not relevant if the defaultValue property is defined with a value.

### See Also

## defaultValue

The BIRT expression that defines the default value of the input parameter.

### Description

The expression that gets evaluated and its resulting value assigned as default value of the input parameter. The default value expression, if defined, is automatically bound to the parameter only if no explicit parameter binding is defined in the data set and its corresponding report parameter.

### See Also

Data Set ParamBinding structureReport Item paramBindings property

## allowNull

Whether a null value is allowed for this parameter.

### Description

If true, the parameter value can be null. If false, the value cannot be null.

### See Also

## isInput

Whether the parameter is of input mode.

### Description

Indicates whether the parameter is of input mode. If true, this is an input parameter; if false, this is not an input parameter.

### See Also

## isOutput

Whether the parameter is of output mode.

### Description

Indicates whether the parameter is of output mode. If true, this is an output parameter; if false, this is not an output parameter.

### See Also