org.h2.expression.condition

Class SimplePredicate

java.lang.Object

org.h2.expression.Expression

org.h2.expression.condition.SimplePredicate

All Implemented Interfaces:

HasSQL, Typed

Direct Known Subclasses:

BooleanTest, NullPredicate, TypePredicate

public abstract class SimplePredicate
extends Expression

Base class for simple predicates.

Field Summary

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
int	getCost() Estimate the cost to process the expression.
Expression	getSubexpression(int index) Returns subexpression with specified index.
int	getSubexpressionCount() Returns count of subexpressions.
TypeInfo	getType() Returns the data type.
boolean	isEverything(ExpressionVisitor visitor) Check if this expression and all sub-expressions can fulfill a criteria.
boolean	isWhenConditionOperand() Returns whether this expression is a right side of condition in a when operand.
void	mapColumns(ColumnResolver resolver, int level, int state) Map the columns of the resolver to expression columns.
boolean	needParentheses() Returns whether this expressions needs to be wrapped in parentheses when it is used as an argument of other expressions.
Expression	optimize(SessionLocal 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(SessionLocal session, int stage) Update an aggregate value.

Methods inherited from class org.h2.expression.Expression

addFilterConditions, createIndexConditions, getAlias, getBooleanValue, getColumnName, getColumnNameForView, getEnclosedSQL, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getTableAlias, getTableName, getUnenclosedSQL, getValue, getWhenSQL, getWhenValue, isConstant, isIdentity, isNullConstant, isValueSet, 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

Method Detail

optimize

public Expression optimize(SessionLocal 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

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

needParentheses

public final boolean needParentheses()

Description copied from class: Expression

Returns whether this expressions needs to be wrapped in parentheses when it is used as an argument of other expressions.

Overrides:

needParentheses in class Expression

Returns:

true if it is

updateAggregate

public void updateAggregate(SessionLocal 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

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

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

getSubexpressionCount

public int getSubexpressionCount()

Description copied from class: Expression

Returns count of subexpressions.

Overrides:

getSubexpressionCount in class Expression

Returns:

count of subexpressions

getSubexpression

public Expression getSubexpression(int index)

Description copied from class: Expression

Returns subexpression with specified index.

Overrides:

getSubexpression in class Expression

Parameters:

index - 0-based index

Returns:

subexpression with specified index, may be null

isWhenConditionOperand

public final boolean isWhenConditionOperand()

Description copied from class: Expression

Returns whether this expression is a right side of condition in a when operand.

Overrides:

isWhenConditionOperand in class Expression

Returns:

true if it is, false otherwise

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