Class SelectUnion

java.lang.Object

org.h2.command.Prepared

org.h2.command.query.Query

org.h2.command.query.SelectUnion

public class SelectUnion
extends Query

Represents a union SELECT statement.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	SelectUnion.LazyResultUnion	Lazy execution for this union.
static enum	SelectUnion.UnionType

Nested classes/interfaces inherited from class Query

Query.OffsetFetch

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	isForUpdate
(package private) final Query	left	The left hand side of the union (the first subquery).
(package private) final Query	right	The right hand side of the union (the second subquery).
private final SelectUnion.UnionType	unionType

Fields inherited from class Query

checkInit, distinct, expressionArray, expressions, fetchExpr, fetchPercent, isPrepared, offsetExpr, orderList, randomAccessResult, resultColumnCount, sort, visibleColumnCount, withTies

Fields inherited from class Prepared

create, parameters, prepareAlways, session, sqlStatement, sqlTokens

Constructor Summary

Constructors

Constructor	Description
SelectUnion(SessionLocal session, SelectUnion.UnionType unionType, Query query, Query right)

Method Summary

Modifier and Type	Method	Description
void	addGlobalCondition(Parameter param, int columnId, int comparisonType)	Add a condition to the query.
boolean	allowGlobalConditions()	Check whether adding condition to the query is allowed.
private Value[]	convert(Value[] values, int columnCount)
private LocalResult	createLocalResult(int columnCount)
void	fireBeforeSelectTriggers()	Call the before triggers on all tables.
double	getCost()	Calculate the cost to execute this query.
LocalResult	getEmptyResult()
Query	getLeft()
String	getPlanSQL(int sqlFlags)	Get the SQL statement with the execution plan.
Query	getRight()
HashSet<Table>	getTables()	Get all tables that are involved in this query.
SelectUnion.UnionType	getUnionType()
void	init()	Initialize the query.
boolean	isConstantQuery()	Check if this query will always return the same value and has no side effects.
boolean	isEverything(ExpressionVisitor visitor)	Check if this expression and all sub-expressions can fulfill a criteria.
boolean	isUnion()	Check if this is a UNION query.
void	mapColumns(ColumnResolver resolver, int level)	Map the columns to the given column resolver.
void	prepare()	Prepare this statement.
protected ResultInterface	queryWithoutCache(long maxRows, ResultTarget target)	Execute the query without checking the cache.
void	setEvaluatable(TableFilter tableFilter, boolean b)	Change the evaluatable flag.
void	setForUpdate(boolean forUpdate)	Set the 'for update' flag.
void	updateAggregate(SessionLocal s, int stage)	Update all aggregate function values.

Methods inherited from class Query

addParameter, appendEndOfQueryToSQL, cleanupOrder, collectDependencies, convertToDistinct, disableCache, exists, finishResult, getColumnCount, getCostAsExpression, getExpressions, getFetch, getIfSingleRow, getMaxDataModificationId, getOffset, getOffsetFetch, getRowDataType, getType, hasOrder, initExpression, initOrder, isAnyDistinct, isFetchPercent, isNeverLazy, isQuery, isRandomAccessResult, isReadOnly, isStandardDistinct, isTransactional, isWithTies, prepareOrder, query, query, queryMeta, setDistinctIfPossible, setFetch, setFetchPercent, setNeverLazy, setOffset, setOrder, setRandomAccessResult, setWithTies, toTable

Methods inherited from class Prepared

checkCanceled, checkParameters, getCteCleanups, getCurrentRowNumber, getObjectId, getParameters, getPersistedObjectId, getSession, getSimpleSQL, getSQL, getSQLTokens, isCacheable, needRecompile, setCommand, setCteCleanups, setCurrentRowNumber, setParameterList, setPersistedObjectId, setPrepareAlways, setRow, setSession, setSQL, toString, update

Methods inherited from class Object

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

Field Details

unionType

private final SelectUnion.UnionType unionType

left

final Query left

The left hand side of the union (the first subquery).

right

final Query right

The right hand side of the union (the second subquery).

isForUpdate

private boolean isForUpdate

Constructor Details

SelectUnion

public SelectUnion(SessionLocal session,
 SelectUnion.UnionType unionType,
 Query query,
 Query right)

Method Details

isUnion

public boolean isUnion()

Description copied from class: Query

Check if this is a UNION query.

Specified by:

isUnion in class Query

Returns:

true if this is a UNION query

getUnionType

public SelectUnion.UnionType getUnionType()

getLeft

public Query getLeft()

getRight

public Query getRight()

convert

private Value[] convert(Value[] values,
 int columnCount)

getEmptyResult

public LocalResult getEmptyResult()

queryWithoutCache

protected ResultInterface queryWithoutCache(long maxRows,
 ResultTarget target)

Description copied from class: Query

Execute the query without checking the cache. If a target is specified, the results are written to it, and the method returns null. If no target is specified, a new LocalResult is created and returned.

Specified by:

queryWithoutCache in class Query

Parameters:

maxRows - the limit as specified in the JDBC method call

target - the target to write results to

Returns:

the result

createLocalResult

private LocalResult createLocalResult(int columnCount)

init

public void init()

Description copied from class: Query

Initialize the query.

Specified by:

init in class Query

prepare

public void prepare()

Description copied from class: Prepared

Prepare this statement.

Overrides:

prepare in class Prepared

getCost

public double getCost()

Description copied from class: Query

Calculate the cost to execute this query.

Specified by:

getCost in class Query

Returns:

the cost

getTables

public HashSet<Table> getTables()

Description copied from class: Query

Get all tables that are involved in this query.

Specified by:

getTables in class Query

Returns:

the set of tables

setForUpdate

public void setForUpdate(boolean forUpdate)

Description copied from class: Query

Set the 'for update' flag.

Specified by:

setForUpdate in class Query

Parameters:

forUpdate - the new setting

mapColumns

public void mapColumns(ColumnResolver resolver,
 int level)

Description copied from class: Query

Map the columns to the given column resolver.

Specified by:

mapColumns in class Query

Parameters:

resolver - the resolver

level - the subquery level (0 is the top level query, 1 is the first subquery level)

setEvaluatable

public void setEvaluatable(TableFilter tableFilter,
 boolean b)

Description copied from class: Query

Change the evaluatable flag. This is used when building the execution plan.

Specified by:

setEvaluatable in class Query

Parameters:

tableFilter - the table filter

b - the new value

addGlobalCondition

public void addGlobalCondition(Parameter param,
 int columnId,
 int comparisonType)

Description copied from class: Query

Add a condition to the query. This is used for views.

Specified by:

addGlobalCondition in class Query

Parameters:

param - the parameter

columnId - the column index (0 meaning the first column)

comparisonType - the comparison type

getPlanSQL

public String getPlanSQL(int sqlFlags)

Description copied from class: Prepared

Get the SQL statement with the execution plan.

Overrides:

getPlanSQL in class Prepared

Parameters:

sqlFlags - formatting flags

Returns:

the execution plan

isEverything

public boolean isEverything(ExpressionVisitor visitor)

Description copied from class: Query

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 Query

Parameters:

visitor - the visitor

Returns:

if the criteria can be fulfilled

updateAggregate

public void updateAggregate(SessionLocal s,
 int stage)

Description copied from class: Query

Update all aggregate function values.

Specified by:

updateAggregate in class Query

Parameters:

s - the session

stage - select stage

fireBeforeSelectTriggers

public void fireBeforeSelectTriggers()

Description copied from class: Query

Call the before triggers on all tables.

Specified by:

fireBeforeSelectTriggers in class Query

allowGlobalConditions

public boolean allowGlobalConditions()

Description copied from class: Query

Check whether adding condition to the query is allowed. This is not allowed for views that have an order by and a limit, as it would affect the returned results.

Specified by:

allowGlobalConditions in class Query

Returns:

true if adding global conditions is allowed

isConstantQuery

public boolean isConstantQuery()

Description copied from class: Query

Check if this query will always return the same value and has no side effects.

Overrides:

isConstantQuery in class Query

Returns:

if this query will always return the same value and has no side effects.