ValueExpression

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

Direct Known Subclasses:

TypedValueExpression
```
public class ValueExpression
extends Expression
```
An expression representing a constant value.

Field Summary
- Fields inherited from class org.h2.expression.Expression
  MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`createIndexConditions(Session session, TableFilter filter)` Create index conditions if possible and attach them to the table filter.
`static ValueExpression`	`get(Value value)` Create a new expression with the given value.
`static ValueExpression`	`getBoolean(boolean value)` Create a new expression with the given boolean value.
`static ValueExpression`	`getBoolean(Value value)` Create a new expression with the given boolean value.
`int`	`getCost()` Estimate the cost to process the expression.
`static ValueExpression`	`getDefault()` Get the DEFAULT expression.
`Expression[]`	`getExpressionColumns(Session session)` If this expression consists of column expressions it should return them.
`Expression`	`getNotIfPossible(Session session)` If it is possible, return the negated expression.
`static ValueExpression`	`getNull()` Get the NULL expression.
`java.lang.StringBuilder`	`getSQL(java.lang.StringBuilder builder, boolean alwaysQuote)` Appends the SQL statement of this expression to the specified builder.
`TypeInfo`	`getType()` Returns the data type.
`Value`	`getValue(Session session)` Return the resulting value for the current row.
`boolean`	`isConstant()` Check if this expression will always return the same value.
`boolean`	`isEverything(ExpressionVisitor visitor)` Check if this expression and all sub-expressions can fulfill a criteria.
`boolean`	`isNullConstant()` Check if this expression will always return the NULL value.
`boolean`	`isValueSet()` Is the value of a parameter set.
`void`	`mapColumns(ColumnResolver resolver, int level, int state)` 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, int stage)` Update an aggregate value.

Methods inherited from class org.h2.expression.Expression
addFilterConditions, getAlias, getBooleanValue, getColumnName, getExpressionColumns, getExpressionColumns, getNonAliasExpression, getNullable, getSchemaName, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getTableName, getUnenclosedSQL, isAutoIncrement, toString, writeExpressions, writeExpressions

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

- Method Detail
  - getNull
```
public static ValueExpression getNull()
```
    Get the NULL expression.
    
    Returns:
    the NULL expression
  - getDefault
```
public static ValueExpression getDefault()
```
    Get the DEFAULT expression.
    
    Returns:
    the DEFAULT expression
  - get
```
public static ValueExpression get(Value value)
```
    Create a new expression with the given value.
    
    Parameters:
    value - the value
    
    Returns:
    the expression
  - getBoolean
```
public static ValueExpression getBoolean(Value value)
```
    Create a new expression with the given boolean value.
    
    Parameters:
    value - the boolean value
    
    Returns:
    the expression
  - getBoolean
```
public static ValueExpression getBoolean(boolean value)
```
    Create a new expression with the given boolean value.
    
    Parameters:
    value - the boolean value
    
    Returns:
    the expression
  - 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 TypeInfo getType()
```
    Description copied from class: Expression
    
    Returns the data type. The data type may not be known before the optimization phase.
    
    Specified by:
    
    getType in class Expression
    
    Returns:
    the data type
  - createIndexConditions
```
public void createIndexConditions(Session session,
                         TableFilter filter)
```
    Description copied from class: Expression
    
    Create index conditions if possible and attach them to the table filter.
    
    Overrides:
    
    createIndexConditions in class Expression
    
    Parameters:
    session - the session
    filter - the table filter
  - getNotIfPossible
```
public Expression getNotIfPossible(Session session)
```
    Description copied from class: Expression
    
    If it is possible, return the negated expression. This is used to optimize NOT expressions: NOT ID>10 can be converted to ID<=10. Returns null if negating is not possible.
    
    Overrides:
    
    getNotIfPossible in class Expression
    
    Parameters:
    session - the session
    
    Returns:
    the negated expression, or null
  - mapColumns
```
public void mapColumns(ColumnResolver resolver,
              int level,
              int state)
```
    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
    state - current state for nesting checks, initial value is Expression.MAP_INITIAL
  - optimize
```
public Expression optimize(Session session)
```
    Description copied from class: Expression
    
    Try to optimize the expression.
    
    Specified by:
    
    optimize in class Expression
    
    Parameters:
    session - the session
    
    Returns:
    the optimized expression
  - isConstant
```
public boolean isConstant()
```
    Description copied from class: Expression
    
    Check if this expression will always return the same value.
    
    Overrides:
    
    isConstant in class Expression
    
    Returns:
    if the expression is constant
  - isNullConstant
```
public boolean isNullConstant()
```
    Description copied from class: Expression
    
    Check if this expression will always return the NULL value.
    
    Overrides:
    
    isNullConstant in class Expression
    
    Returns:
    if the expression is constant NULL value
  - isValueSet
```
public boolean isValueSet()
```
    Description copied from class: Expression
    
    Is the value of a parameter set.
    
    Overrides:
    
    isValueSet in class Expression
    
    Returns:
    true if set
  - 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
  - getSQL
```
public java.lang.StringBuilder getSQL(java.lang.StringBuilder builder,
                             boolean alwaysQuote)
```
    Description copied from class: Expression
    
    Appends the SQL statement of this expression to the specified builder. This may not always be the original SQL statement, specially after optimization.
    
    Specified by:
    
    getSQL in class Expression
    
    Parameters:
    builder - string builder
    alwaysQuote - quote all identifiers
    
    Returns:
    the specified string builder
  - updateAggregate
```
public void updateAggregate(Session session,
                   int stage)
```
    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
    stage - select stage
  - 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
  - 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

Class ValueExpression

Field Summary

Fields inherited from class org.h2.expression.Expression

Method Summary

Methods inherited from class org.h2.expression.Expression

Methods inherited from class java.lang.Object

Method Detail

getNull

getDefault

get

getBoolean

getBoolean

getValue

getType

createIndexConditions

getNotIfPossible

mapColumns

optimize

isConstant

isNullConstant

isValueSet

setEvaluatable

getSQL

updateAggregate

isEverything

getCost

getExpressionColumns