JavaFunction

java.lang.Object
- org.h2.expression.Expression
- - org.h2.expression.JavaFunction

All Implemented Interfaces:

FunctionCall
```
public class JavaFunction
extends Expression
implements FunctionCall
```
This class wraps a user-defined function.

Constructor Summary

Constructors
Constructor and Description

JavaFunction(FunctionAlias functionAlias, Expression[] args)

Constructors
Constructor and Description
`JavaFunction(FunctionAlias functionAlias, Expression[] args)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Expression[]`	`getArgs()` Get the function arguments.
`int`	`getCost()` Estimate the cost to process the expression.
`int`	`getDisplaySize()` Get the display size of this expression.
`Expression[]`	`getExpressionColumns(Session session)` If this expression consists of column expressions it should return them.
`java.lang.String`	`getName()` Get the name of the function.
`long`	`getPrecision()` Get the precision of this expression.
`int`	`getScale()` Get the scale of this expression.
`java.lang.String`	`getSQL()` Get the SQL statement of this expression.
`int`	`getType()` Return the data type.
`Value`	`getValue(Session session)` Return the resulting value for the current row.
`ValueResultSet`	`getValueForColumnList(Session session, Expression[] argList)` Get an empty result set with the column names set.
`boolean`	`isBufferResultSetToLocalTemp()` Should the return value ResultSet be buffered in a local temporary file?
`boolean`	`isDeterministic()` Whether the function always returns the same result for the same parameters.
`boolean`	`isEverything(ExpressionVisitor visitor)` Check if this expression and all sub-expressions can fulfill a criteria.
`void`	`mapColumns(ColumnResolver resolver, int level)` Map the columns of the resolver to expression columns.
`Expression`	`optimize(Session session)` Try to optimize the expression.
`void`	`setEvaluatable(TableFilter tableFilter, boolean b)` Tell the expression columns whether the table filter can return values now.
`void`	`updateAggregate(Session session)` Update an aggregate value.

Methods inherited from class org.h2.expression.Expression
addFilterConditions, createIndexConditions, getAlias, getBooleanValue, getColumnName, getExpressionColumns, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getTableAlias, getTableName, isAutoIncrement, isConstant, isValueSet, isWildcard, toString

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

- Constructor Detail
  - JavaFunction
```
public JavaFunction(FunctionAlias functionAlias,
                    Expression[] args)
```
- Method Detail
  - getValue
```
public Value getValue(Session session)
```
    Description copied from class: Expression
    
    Return the resulting value for the current row.
    
    Specified by:
    
    getValue in class Expression
    
    Parameters:
    
    session - the session
    
    Returns:
    
    the result
  - getType
```
public int getType()
```
    Description copied from class: Expression
    
    Return the data type. The data type may not be known before the optimization phase.
    
    Specified by:
    
    getType in interface FunctionCall
    
    Specified by:
    
    getType in class Expression
    
    Returns:
    
    the type
  - mapColumns
```
public void mapColumns(ColumnResolver resolver,
                       int level)
```
    Description copied from class: Expression
    
    Map the columns of the resolver to expression columns.
    
    Specified by:
    
    mapColumns in class Expression
    
    Parameters:
    
    resolver - the column resolver
    
    level - the subquery nesting level
  - optimize
```
public Expression optimize(Session session)
```
    Description copied from class: Expression
    
    Try to optimize the expression.
    
    Specified by:
    
    optimize in interface FunctionCall
    
    Specified by:
    
    optimize in class Expression
    
    Parameters:
    
    session - the session
    
    Returns:
    
    the optimized expression
  - setEvaluatable
```
public void setEvaluatable(TableFilter tableFilter,
                           boolean b)
```
    Description copied from class: Expression
    
    Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.
    
    Specified by:
    
    setEvaluatable in class Expression
    
    Parameters:
    
    tableFilter - the table filter
    
    b - true if the table filter can return value
  - getScale
```
public int getScale()
```
    Description copied from class: Expression
    
    Get the scale of this expression.
    
    Specified by:
    
    getScale in class Expression
    
    Returns:
    
    the scale
  - getPrecision
```
public long getPrecision()
```
    Description copied from class: Expression
    
    Get the precision of this expression.
    
    Specified by:
    
    getPrecision in class Expression
    
    Returns:
    
    the precision
  - getDisplaySize
```
public int getDisplaySize()
```
    Description copied from class: Expression
    
    Get the display size of this expression.
    
    Specified by:
    
    getDisplaySize in class Expression
    
    Returns:
    
    the display size
  - getSQL
```
public java.lang.String getSQL()
```
    Description copied from class: Expression
    
    Get the SQL statement of this expression. This may not always be the original SQL statement, specially after optimization.
    
    Specified by:
    
    getSQL in interface FunctionCall
    
    Specified by:
    
    getSQL in class Expression
    
    Returns:
    
    the SQL statement
  - updateAggregate
```
public void updateAggregate(Session session)
```
    Description copied from class: Expression
    
    Update an aggregate value. This method is called at statement execution time. It is usually called once for each row, but if the expression is used multiple times (for example in the column list, and as part of the HAVING expression) it is called multiple times - the row counter needs to be used to make sure the internal state is only updated once.
    
    Specified by:
    
    updateAggregate in class Expression
    
    Parameters:
    
    session - the session
  - getName
```
public java.lang.String getName()
```
    Description copied from interface: FunctionCall
    
    Get the name of the function.
    
    Specified by:
    
    getName in interface FunctionCall
    
    Returns:
    
    the name
  - getValueForColumnList
```
public ValueResultSet getValueForColumnList(Session session,
                                            Expression[] argList)
```
    Description copied from interface: FunctionCall
    
    Get an empty result set with the column names set.
    
    Specified by:
    
    getValueForColumnList in interface FunctionCall
    
    Parameters:
    
    session - the session
    
    argList - the argument list (some arguments may be null)
    
    Returns:
    
    the empty result set
  - getArgs
```
public Expression[] getArgs()
```
    Description copied from interface: FunctionCall
    
    Get the function arguments.
    
    Specified by:
    
    getArgs in interface FunctionCall
    
    Returns:
    
    argument list
  - isEverything
```
public boolean isEverything(ExpressionVisitor visitor)
```
    Description copied from class: Expression
    
    Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.
    
    Specified by:
    
    isEverything in class Expression
    
    Parameters:
    
    visitor - the visitor
    
    Returns:
    
    if the criteria can be fulfilled
  - getCost
```
public int getCost()
```
    Description copied from class: Expression
    
    Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.
    
    Specified by:
    
    getCost in class Expression
    
    Returns:
    
    the estimated cost
  - isDeterministic
```
public boolean isDeterministic()
```
    Description copied from interface: FunctionCall
    
    Whether the function always returns the same result for the same parameters.
    
    Specified by:
    
    isDeterministic in interface FunctionCall
    
    Returns:
    
    true if it does
  - getExpressionColumns
```
public Expression[] getExpressionColumns(Session session)
```
    Description copied from class: Expression
    
    If this expression consists of column expressions it should return them.
    
    Overrides:
    
    getExpressionColumns in class Expression
    
    Parameters:
    
    session - the session
    
    Returns:
    
    array of expression columns if applicable, null otherwise
  - isBufferResultSetToLocalTemp
```
public boolean isBufferResultSetToLocalTemp()
```
    Description copied from interface: FunctionCall
    
    Should the return value ResultSet be buffered in a local temporary file?
    
    Specified by:
    
    isBufferResultSetToLocalTemp in interface FunctionCall
    
    Returns:
    
    true if it should be.

Class JavaFunction

Constructor Summary

Method Summary

Methods inherited from class org.h2.expression.Expression

Methods inherited from class java.lang.Object

Constructor Detail

JavaFunction

Method Detail

getValue

getType

mapColumns

optimize

setEvaluatable

getScale

getPrecision

getDisplaySize

getSQL

updateAggregate

getName

getValueForColumnList

getArgs

isEverything

getCost

isDeterministic

getExpressionColumns

isBufferResultSetToLocalTemp