Select

java.lang.Object
- org.h2.command.Prepared
- - org.h2.command.query.Query
  - - org.h2.command.query.Select

```
public class Select
extends Query
```
This class represents a simple SELECT statement. For each select statement, visibleColumnCount <= distinctColumnCount <= expressionCount. The expression list count could include ORDER BY and GROUP BY expressions that are not in the select list. The call sequence is init(), mapColumns() if it's a subquery, prepare().

Field Summary
- Fields inherited from class org.h2.command.Prepared
  create, parameters, prepareAlways, session, sqlStatement, sqlTokens

Constructor Summary

Constructors
Constructor and Description

Select(SessionLocal session, Select parentSelect)

Constructors
Constructor and Description
`Select(SessionLocal session, Select parentSelect)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addCondition(Expression cond)` Add a condition to the list of conditions.
`void`	`addGlobalCondition(Parameter param, int columnId, int comparisonType)` Add a condition to the query.
`void`	`addTableFilter(TableFilter filter, boolean isTop)` Add a table to the query.
`boolean`	`addWindow(java.lang.String name, Window window)` Adds a named window definition.
`boolean`	`allowGlobalConditions()` Check whether adding condition to the query is allowed.
`void`	`fireBeforeSelectTriggers()` Call the before triggers on all tables.
`Expression`	`getCondition()`
`double`	`getCost()` Calculate the cost to execute this query.
`java.util.ArrayList<Expression>`	`getGroupBy()`
`SelectGroups`	`getGroupDataIfCurrent(boolean window)` Get the group data if there is currently a group-by active.
`Expression`	`getHaving()`
`Expression`	`getIfSingleRow()` If this query is determined as a single-row query, returns a replacement expression.
`Select`	`getParentSelect()` Returns parent select, or null.
`java.lang.String`	`getPlanSQL(int sqlFlags)` Get the SQL statement with the execution plan.
`Expression`	`getQualify()`
`SortOrder`	`getSortOrder()`
`java.util.HashSet<Table>`	`getTables()` Get all tables that are involved in this query.
`java.util.ArrayList<TableFilter>`	`getTopFilters()`
`TableFilter`	`getTopTableFilter()`
`Window`	`getWindow(java.lang.String name)` Returns a window with specified name, or null.
`void`	`init()` Initialize the query.
`boolean`	`isAnyDistinct()`
`boolean`	`isCacheable()`
`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`	`isGroupQuery()` Checks if this query is a group query.
`boolean`	`isGroupWindowStage2()` Checks if window stage of group window query is performed.
`boolean`	`isQuickAggregateQuery()` Check if this is an aggregate query with direct lookup, for example a query of the type SELECT COUNT(*) FROM TEST or SELECT MAX(ID) FROM TEST.
`boolean`	`isUnion()` Check if this is a UNION query.
`boolean`	`isWindowQuery()` Checks if this query contains window functions.
`void`	`mapColumns(ColumnResolver resolver, int level)` 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`	`setDistinct()` Set the distinct flag.
`void`	`setDistinct(Expression[] distinctExpressions)` Set the DISTINCT ON expressions.
`void`	`setEvaluatable(TableFilter tableFilter, boolean b)` Change the evaluatable flag.
`void`	`setExplicitTable()` Convert this SELECT to an explicit table (TABLE tableName).
`void`	`setExpressions(java.util.ArrayList<Expression> expressions)`
`void`	`setForUpdate(boolean b)` Set the 'for update' flag.
`void`	`setGroupBy(java.util.ArrayList<Expression> group)`
`void`	`setGroupQuery()` Set when SELECT statement contains (non-window) aggregate functions, GROUP BY clause or HAVING clause.
`void`	`setHaving(Expression having)`
`void`	`setQualify(Expression qualify)`
`void`	`setWildcard()` Sets a wildcard expression as in "SELECT * FROM TEST".
`void`	`setWindowQuery()` Called if this query contains window functions.
`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, getMaxDataModificationId, getOffset, getRowDataType, getType, hasOrder, isFetchPercent, isNeverLazy, isQuery, isRandomAccessResult, isReadOnly, isStandardDistinct, isTransactional, isWithTies, prepare, query, query, queryMeta, setDistinctIfPossible, setFetch, setFetchPercent, setNeverLazy, setOffset, setOrder, setRandomAccessResult, setWithTies, toTable

Methods inherited from class org.h2.command.Prepared
checkCanceled, checkParameters, getCteCleanups, getCurrentRowNumber, getObjectId, getParameters, getPersistedObjectId, getSession, getSimpleSQL, getSQL, getSQLTokens, isWithParamValues, needRecompile, setCommand, setCteCleanups, 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 Detail
  - Select
```
public Select(SessionLocal session,
              Select parentSelect)
```
- Method Detail
  - 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
  - addTableFilter
```
public void addTableFilter(TableFilter filter,
                           boolean isTop)
```
    Add a table to the query.
    
    Parameters:
    
    filter - the table to add
    
    isTop - if the table can be the first table in the query plan
  - getTopFilters
```
public java.util.ArrayList<TableFilter> getTopFilters()
```
  - setExpressions
```
public void setExpressions(java.util.ArrayList<Expression> expressions)
```
  - setExplicitTable
```
public void setExplicitTable()
```
    Convert this SELECT to an explicit table (TABLE tableName).
  - setWildcard
```
public void setWildcard()
```
    Sets a wildcard expression as in "SELECT * FROM TEST".
  - setGroupQuery
```
public void setGroupQuery()
```
    Set when SELECT statement contains (non-window) aggregate functions, GROUP BY clause or HAVING clause.
  - setWindowQuery
```
public void setWindowQuery()
```
    Called if this query contains window functions.
  - setGroupBy
```
public void setGroupBy(java.util.ArrayList<Expression> group)
```
  - getGroupBy
```
public java.util.ArrayList<Expression> getGroupBy()
```
  - getGroupDataIfCurrent
```
public SelectGroups getGroupDataIfCurrent(boolean window)
```
    Get the group data if there is currently a group-by active.
    
    Parameters:
    
    window - is this a window function
    
    Returns:
    
    the grouped data
  - setDistinct
```
public void setDistinct()
```
    Set the distinct flag.
  - setDistinct
```
public void setDistinct(Expression[] distinctExpressions)
```
    Set the DISTINCT ON expressions.
    
    Parameters:
    
    distinctExpressions - array of expressions
  - isAnyDistinct
```
public boolean isAnyDistinct()
```
    Overrides:
    
    isAnyDistinct in class Query
    
    Returns:
    
    whether this query is a DISTINCT or DISTINCT ON (...) query
  - addWindow
```
public boolean addWindow(java.lang.String name,
                         Window window)
```
    Adds a named window definition.
    
    Parameters:
    
    name - name
    
    window - window definition
    
    Returns:
    
    true if a new definition was added, false if old definition was replaced
  - getWindow
```
public Window getWindow(java.lang.String name)
```
    Returns a window with specified name, or null.
    
    Parameters:
    
    name - name of the window
    
    Returns:
    
    the window with specified name, or null
  - addCondition
```
public void addCondition(Expression cond)
```
    Add a condition to the list of conditions.
    
    Parameters:
    
    cond - the condition to add
  - getCondition
```
public Expression getCondition()
```
  - 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 java.util.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
  - fireBeforeSelectTriggers
```
public void fireBeforeSelectTriggers()
```
    Description copied from class: Query
    
    Call the before triggers on all tables.
    
    Specified by:
    
    fireBeforeSelectTriggers in class Query
  - getPlanSQL
```
public java.lang.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
  - setHaving
```
public void setHaving(Expression having)
```
  - getHaving
```
public Expression getHaving()
```
  - setQualify
```
public void setQualify(Expression qualify)
```
  - getQualify
```
public Expression getQualify()
```
  - getTopTableFilter
```
public TableFilter getTopTableFilter()
```
  - setForUpdate
```
public void setForUpdate(boolean b)
```
    Description copied from class: Query
    
    Set the 'for update' flag.
    
    Specified by:
    
    setForUpdate in class Query
    
    Parameters:
    
    b - 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
  - isQuickAggregateQuery
```
public boolean isQuickAggregateQuery()
```
    Check if this is an aggregate query with direct lookup, for example a query of the type SELECT COUNT(*) FROM TEST or SELECT MAX(ID) FROM TEST.
    
    Returns:
    
    true if a direct lookup is possible
  - isGroupQuery
```
public boolean isGroupQuery()
```
    Checks if this query is a group query.
    
    Returns:
    
    whether this query is a group query.
  - isWindowQuery
```
public boolean isWindowQuery()
```
    Checks if this query contains window functions.
    
    Returns:
    
    whether this query contains window functions
  - isGroupWindowStage2
```
public boolean isGroupWindowStage2()
```
    Checks if window stage of group window query is performed. If true, column resolver may not be used.
    
    Returns:
    
    true if window stage of group window query is performed
  - 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
  - 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
  - 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
  - isCacheable
```
public boolean isCacheable()
```
    Overrides:
    
    isCacheable in class Prepared
  - 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
  - getSortOrder
```
public SortOrder getSortOrder()
```
  - getParentSelect
```
public Select getParentSelect()
```
    Returns parent select, or null.
    
    Returns:
    
    parent select, or null
  - 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.
  - getIfSingleRow
```
public Expression getIfSingleRow()
```
    Description copied from class: Query
    
    If this query is determined as a single-row query, returns a replacement expression.
    
    Overrides:
    
    getIfSingleRow in class Query
    
    Returns:
    
    the expression, or null

Class Select

Field Summary

Fields inherited from class org.h2.command.Prepared

Constructor Summary

Method Summary

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

Methods inherited from class org.h2.command.Prepared

Methods inherited from class java.lang.Object

Constructor Detail

Select

Method Detail

isUnion

addTableFilter

getTopFilters

setExpressions

setExplicitTable

setWildcard

setGroupQuery

setWindowQuery

setGroupBy

getGroupBy

getGroupDataIfCurrent

setDistinct

setDistinct

isAnyDistinct

addWindow

getWindow

addCondition

getCondition

queryWithoutCache

init

prepareExpressions

preparePlan

getCost

getTables

fireBeforeSelectTriggers

getPlanSQL

setHaving

getHaving

setQualify

getQualify

getTopTableFilter

setForUpdate

mapColumns

setEvaluatable

isQuickAggregateQuery

isGroupQuery

isWindowQuery

isGroupWindowStage2

addGlobalCondition

updateAggregate

isEverything

isCacheable

allowGlobalConditions

getSortOrder

getParentSelect

isConstantQuery

getIfSingleRow