FunctionParameter (Apache Calcite API)

```
public interface FunctionParameter
```
Parameter to a Function.
NOTE: We'd have called it Parameter but the overlap with Parameter was too confusing.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.lang.String`	`getName()`	Name of the parameter.
`int`	`getOrdinal()`	Zero-based ordinal of this parameter within the member's parameter list.
`RelDataType`	`getType(RelDataTypeFactory typeFactory)`	Returns the type of this parameter.
`boolean`	`isOptional()`	Returns whether this parameter is optional.

- Method Detail
  - getOrdinal
```
int getOrdinal()
```
    Zero-based ordinal of this parameter within the member's parameter list.
    
    Returns:
    
    Parameter ordinal
  - getName
```
java.lang.String getName()
```
    Name of the parameter.
    
    Returns:
    
    Parameter name
  - getType
```
RelDataType getType(RelDataTypeFactory typeFactory)
```
    Returns the type of this parameter.
    
    Parameters:
    
    typeFactory - Type factory to be used to create the type
    
    Returns:
    
    Parameter type.
  - isOptional
```
boolean isOptional()
```
    Returns whether this parameter is optional.
    If true, the value of the parameter can be supplied using the DEFAULT SQL keyword, or it can be omitted from a function called using argument assignment, or the function can be called with fewer parameters (if all parameters after it are optional too).
    If a parameter is optional its default value is NULL. We may in future allow functions to specify other default values.