Package org.h2.expression

Class Operation0

java.lang.Object

org.h2.expression.Expression

org.h2.expression.Operation0

All Implemented Interfaces:

HasSQL, Typed

Direct Known Subclasses:

CurrentDateTimeValueFunction, CurrentGeneralValueSpecification, DomainValueExpression, OnDuplicateKeyValues, Parameter, Rownum, SequenceValue, SysInfoFunction, ValueExpression, Variable

public abstract class Operation0
extends Expression

Operation without subexpressions.

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

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Operation0()

Method Summary

Modifier and Type	Method	Description
void	mapColumns(ColumnResolver resolver, int level, int state)	Map the columns of the resolver to expression columns.
Expression	optimize(SessionLocal session)	Try to optimize the expression.
void	setEvaluatable(TableFilter tableFilter, boolean value)	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, getCost, getEnclosedSQL, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getTableName, getType, getTypeIfStaticallyKnown, getUnenclosedSQL, getValue, getWhenSQL, getWhenValue, isConstant, isEverything, isIdentity, isNullConstant, isValueSet, 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

Constructor Details

Operation0

protected Operation0()

Method Details

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(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 value)

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

value - true if the table filter can return value

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