org.h2.expression

Class ValueExpression

java.lang.Object

org.h2.expression.Expression

org.h2.expression.Operation0

org.h2.expression.ValueExpression

All Implemented Interfaces:

HasSQL, Typed

Direct Known Subclasses:

TypedValueExpression

public class ValueExpression
extends Operation0

An expression representing a constant value.

Field Summary

Fields

Modifier and Type	Field and Description
static ValueExpression	DEFAULT This special expression represents the default value.
static ValueExpression	FALSE The expression represents ValueBoolean.FALSE.
static ValueExpression	NULL The expression represents ValueNull.INSTANCE.
static ValueExpression	TRUE The expression represents ValueBoolean.TRUE.

Fields inherited from class org.h2.expression.Expression

AUTO_PARENTHESES, MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL, WITH_PARENTHESES, WITHOUT_PARENTHESES

Fields inherited from interface org.h2.util.HasSQL

ADD_PLAN_INFORMATION, DEFAULT_SQL_FLAGS, NO_CASTS, QUOTE_ONLY_WHEN_REQUIRED, REPLACE_LOBS_FOR_TRACE, TRACE_SQL_FLAGS

Method Summary

Modifier and Type	Method and Description
void	createIndexConditions(SessionLocal 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.
Expression	getNotIfPossible(SessionLocal session) If it is possible, return the negated expression.
TypeInfo	getType() Returns the data type.
java.lang.StringBuilder	getUnenclosedSQL(java.lang.StringBuilder builder, int sqlFlags) Get the SQL statement of this expression.
Value	getValue(SessionLocal 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.

Methods inherited from class org.h2.expression.Operation0

mapColumns, optimize, setEvaluatable, updateAggregate

Methods inherited from class org.h2.expression.Expression

addFilterConditions, getAlias, getBooleanValue, getColumnName, getColumnNameForView, getEnclosedSQL, getNonAliasExpression, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getTableName, getWhenSQL, getWhenValue, isIdentity, isWhenConditionOperand, needParentheses, optimizeCondition, toString, writeExpressions, writeExpressions

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.h2.util.HasSQL

getTraceSQL

Field Detail

NULL

public static final ValueExpression NULL

The expression represents ValueNull.INSTANCE.

DEFAULT

public static final ValueExpression DEFAULT

This special expression represents the default value. It is used for UPDATE statements of the form SET COLUMN = DEFAULT. The value is ValueNull.INSTANCE, but should never be accessed.

TRUE

public static final ValueExpression TRUE

The expression represents ValueBoolean.TRUE.

FALSE

public static final ValueExpression FALSE

The expression represents ValueBoolean.FALSE.

Method Detail

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(SessionLocal 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 be unknown before the optimization phase.

Specified by:

getType in interface Typed

Specified by:

getType in class Expression

Returns:

the data type

createIndexConditions

public void createIndexConditions(SessionLocal 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(SessionLocal 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

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

getUnenclosedSQL

public java.lang.StringBuilder getUnenclosedSQL(java.lang.StringBuilder builder,
                                                int sqlFlags)

Description copied from class: Expression

Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are never appended.

Specified by:

getUnenclosedSQL in class Expression

Parameters:

builder - string builder

sqlFlags - formatting flags

Returns:

the specified string builder

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