Coalesce (NanoDB SQL Relational Database 0.1-SNAPSHOT API)

java.lang.Object
- edu.caltech.nanodb.functions.Function
- - edu.caltech.nanodb.functions.ScalarFunction
  - - edu.caltech.nanodb.functions.SimpleFunction
    - - edu.caltech.nanodb.functions.Coalesce

All Implemented Interfaces:

java.lang.Cloneable
```
public class Coalesce
extends SimpleFunction
```
Implementation of the COALESCE(a, b, ...) SQL function, returns the first non-NULL argument. The function's return-type is reported to be whatever the first argument's type is. This function requires at least one argument to be specified.

Constructor Summary

Constructors
Constructor Description

Coalesce()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`java.lang.Object`	`evaluate(Environment env, java.util.List<Expression> args)`	Evaluates the function.
`ColumnType`	`getReturnType(java.util.List<Expression> args, Schema schema)`	Returns the column type of the resulting column after applying the function.

Methods inherited from class edu.caltech.nanodb.functions.Function
clone

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Coalesce
```
public Coalesce()
```
- Method Detail
  - getReturnType
```
public ColumnType getReturnType(java.util.List<Expression> args,
                                Schema schema)
```
    Description copied from class: ScalarFunction
    
    Returns the column type of the resulting column after applying the function. This generally depends on the column type of the inputs.
    
    Specified by:
    
    getReturnType in class ScalarFunction
    
    Parameters:
    
    args - the arguments to the function call
    
    schema - the schema of the table
    
    Returns:
    
    the column type of the resulting column
  - evaluate
```
public java.lang.Object evaluate(Environment env,
                                 java.util.List<Expression> args)
```
    Description copied from class: SimpleFunction
    
    Evaluates the function. Should be called at runtime for every function call.
    
    Specified by:
    
    evaluate in class SimpleFunction
    
    Parameters:
    
    env - Environment, in which the arguments are evaluated
    
    args - Arguments for this function
    
    Returns:
    
    The value of the function