Package org.h2.command.query

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
static enum	SelectUnion.UnionType

Field Summary

Fields inherited from class org.h2.command.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.
void	fireBeforeSelectTriggers()	Call the before triggers on all tables.
double	getCost()	Calculate the cost to execute this query.
LocalResult	getEmptyResult()
ForUpdate	getForUpdate()	Returns FOR UPDATE clause, if any.
Query	getLeft()
StringBuilder	getPlanSQL(StringBuilder builder, int sqlFlags)	Appends 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, boolean outer)	Map the columns to the given column resolver.
void	prepareExpressions()
void	preparePlan()
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(ForUpdate forUpdate)	Set the FOR UPDATE clause.
void	updateAggregate(SessionLocal s, int stage)	Update all aggregate function values.

Methods inherited from class org.h2.command.query.Query

collectDependencies, disableCache, exists, getColumnCount, getCostAsExpression, getExpressions, getFetch, getIfSingleRow, getMaxDataModificationId, getOffset, getOuterQueryScope, getRowDataType, getType, hasOrder, isAnyDistinct, isFetchPercent, isNeverLazy, isQuery, isRandomAccessResult, isReadOnly, isRetryable, isStandardDistinct, isTransactional, isWithTies, prepare, query, query, queryMeta, setDistinctIfPossible, setFetch, setFetchPercent, setNeverLazy, setOffset, setOrder, setOuterQueryScope, setRandomAccessResult, setWithClause, setWithTies, toTable, writeWithList

Methods inherited from class org.h2.command.Prepared

checkCanceled, checkParameters, getCurrentRowNumber, getDatabase, getObjectId, getParameters, getPersistedObjectId, getPlanSQL, getSession, getSimpleSQL, getSQL, getSQLTokens, isCacheable, isWithParamValues, needRecompile, setCommand, setCurrentRowNumber, setParameterList, setPersistedObjectId, setPrepareAlways, setRow, setSession, setSQL, setWithParamValues, toString, update

Methods inherited from class java.lang.Object

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

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()

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

init

public void init()

Description copied from class: Query

Initialize the query.

Specified by:

init in class Query

prepareExpressions

public void prepareExpressions()

Specified by:

prepareExpressions in class Query

preparePlan

public void preparePlan()

Specified by:

preparePlan in class Query

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

getForUpdate

public ForUpdate getForUpdate()

Description copied from class: Query

Returns FOR UPDATE clause, if any.

Overrides:

getForUpdate in class Query

Returns:

FOR UPDATE clause or null

setForUpdate

public void setForUpdate(ForUpdate forUpdate)

Description copied from class: Query

Set the FOR UPDATE clause.

Specified by:

setForUpdate in class Query

Parameters:

forUpdate - the new FOR UPDATE clause

mapColumns

public void mapColumns(ColumnResolver resolver,
 int level,
 boolean outer)

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)

outer - whether this method was called from the outer query

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 StringBuilder getPlanSQL(StringBuilder builder,
 int sqlFlags)

Description copied from class: Prepared

Appends the SQL statement with the execution plan.

Overrides:

getPlanSQL in class Prepared

Parameters:

builder - string builder

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.