Select (H2 Database Engine 2.0.0 API)

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().

作者:

Thomas Mueller, Joel Turkel (Group sorted query)

字段概要
- 从类继承的字段 org.h2.command.Prepared
  create, parameters, prepareAlways, session, sqlStatement, sqlTokens

构造器概要

构造器
构造器和说明

Select(SessionLocal session, Select parentSelect)

构造器
构造器和说明
`Select(SessionLocal session, Select parentSelect)`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`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(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.
`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.
`String`	`getPlanSQL(int sqlFlags)` Get the SQL statement with the execution plan.
`Expression`	`getQualify()`
`SortOrder`	`getSortOrder()`
`HashSet<Table>`	`getTables()` Get all tables that are involved in this query.
`ArrayList<TableFilter>`	`getTopFilters()`
`TableFilter`	`getTopTableFilter()`
`Window`	`getWindow(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(ArrayList<Expression> expressions)`
`void`	`setForUpdate(boolean b)` Set the 'for update' flag.
`void`	`setGroupBy(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.

从类继承的方法 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

从类继承的方法 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

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- 构造器详细资料
  - Select
```
public Select(SessionLocal session,
              Select parentSelect)
```
- 方法详细资料
  - isUnion
```
public boolean isUnion()
```
    从类复制的说明: Query
    
    Check if this is a UNION query.
    
    指定者:
    
    isUnion 在类中 Query
    
    返回:
    
    true if this is a UNION query
  - addTableFilter
```
public void addTableFilter(TableFilter filter,
                           boolean isTop)
```
    Add a table to the query.
    
    参数:
    
    filter - the table to add
    
    isTop - if the table can be the first table in the query plan
  - getTopFilters
```
public ArrayList<TableFilter> getTopFilters()
```
  - setExpressions
```
public void setExpressions(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(ArrayList<Expression> group)
```
  - getGroupBy
```
public ArrayList<Expression> getGroupBy()
```
  - getGroupDataIfCurrent
```
public SelectGroups getGroupDataIfCurrent(boolean window)
```
    Get the group data if there is currently a group-by active.
    
    参数:
    
    window - is this a window function
    
    返回:
    
    the grouped data
  - setDistinct
```
public void setDistinct()
```
    Set the distinct flag.
  - setDistinct
```
public void setDistinct(Expression[] distinctExpressions)
```
    Set the DISTINCT ON expressions.
    
    参数:
    
    distinctExpressions - array of expressions
  - isAnyDistinct
```
public boolean isAnyDistinct()
```
    覆盖:
    
    isAnyDistinct 在类中 Query
    
    返回:
    
    whether this query is a DISTINCT or DISTINCT ON (...) query
  - addWindow
```
public boolean addWindow(String name,
                         Window window)
```
    Adds a named window definition.
    
    参数:
    
    name - name
    
    window - window definition
    
    返回:
    
    true if a new definition was added, false if old definition was replaced
  - getWindow
```
public Window getWindow(String name)
```
    Returns a window with specified name, or null.
    
    参数:
    
    name - name of the window
    
    返回:
    
    the window with specified name, or null
  - addCondition
```
public void addCondition(Expression cond)
```
    Add a condition to the list of conditions.
    
    参数:
    
    cond - the condition to add
  - getCondition
```
public Expression getCondition()
```
  - queryWithoutCache
```
protected ResultInterface queryWithoutCache(long maxRows,
                                            ResultTarget target)
```
    从类复制的说明: 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.
    
    指定者:
    
    queryWithoutCache 在类中 Query
    
    参数:
    
    maxRows - the limit as specified in the JDBC method call
    
    target - the target to write results to
    
    返回:
    
    the result
  - init
```
public void init()
```
    从类复制的说明: Query
    
    Initialize the query.
    
    指定者:
    
    init 在类中 Query
  - prepareExpressions
```
public void prepareExpressions()
```
    指定者:
    
    prepareExpressions 在类中 Query
  - preparePlan
```
public void preparePlan()
```
    指定者:
    
    preparePlan 在类中 Query
  - getCost
```
public double getCost()
```
    从类复制的说明: Query
    
    Calculate the cost to execute this query.
    
    指定者:
    
    getCost 在类中 Query
    
    返回:
    
    the cost
  - getTables
```
public HashSet<Table> getTables()
```
    从类复制的说明: Query
    
    Get all tables that are involved in this query.
    
    指定者:
    
    getTables 在类中 Query
    
    返回:
    
    the set of tables
  - fireBeforeSelectTriggers
```
public void fireBeforeSelectTriggers()
```
    从类复制的说明: Query
    
    Call the before triggers on all tables.
    
    指定者:
    
    fireBeforeSelectTriggers 在类中 Query
  - getPlanSQL
```
public String getPlanSQL(int sqlFlags)
```
    从类复制的说明: Prepared
    
    Get the SQL statement with the execution plan.
    
    覆盖:
    
    getPlanSQL 在类中 Prepared
    
    参数:
    
    sqlFlags - formatting flags
    
    返回:
    
    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)
```
    从类复制的说明: Query
    
    Set the 'for update' flag.
    
    指定者:
    
    setForUpdate 在类中 Query
    
    参数:
    
    b - the new setting
  - mapColumns
```
public void mapColumns(ColumnResolver resolver,
                       int level)
```
    从类复制的说明: Query
    
    Map the columns to the given column resolver.
    
    指定者:
    
    mapColumns 在类中 Query
    
    参数:
    
    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)
```
    从类复制的说明: Query
    
    Change the evaluatable flag. This is used when building the execution plan.
    
    指定者:
    
    setEvaluatable 在类中 Query
    
    参数:
    
    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.
    
    返回:
    
    true if a direct lookup is possible
  - isGroupQuery
```
public boolean isGroupQuery()
```
    Checks if this query is a group query.
    
    返回:
    
    whether this query is a group query.
  - isWindowQuery
```
public boolean isWindowQuery()
```
    Checks if this query contains window functions.
    
    返回:
    
    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.
    
    返回:
    
    true if window stage of group window query is performed
  - addGlobalCondition
```
public void addGlobalCondition(Parameter param,
                               int columnId,
                               int comparisonType)
```
    从类复制的说明: Query
    
    Add a condition to the query. This is used for views.
    
    指定者:
    
    addGlobalCondition 在类中 Query
    
    参数:
    
    param - the parameter
    
    columnId - the column index (0 meaning the first column)
    
    comparisonType - the comparison type
  - updateAggregate
```
public void updateAggregate(SessionLocal s,
                            int stage)
```
    从类复制的说明: Query
    
    Update all aggregate function values.
    
    指定者:
    
    updateAggregate 在类中 Query
    
    参数:
    
    s - the session
    
    stage - select stage
  - isEverything
```
public boolean isEverything(ExpressionVisitor visitor)
```
    从类复制的说明: Query
    
    Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.
    
    指定者:
    
    isEverything 在类中 Query
    
    参数:
    
    visitor - the visitor
    
    返回:
    
    if the criteria can be fulfilled
  - isCacheable
```
public boolean isCacheable()
```
    覆盖:
    
    isCacheable 在类中 Prepared
  - allowGlobalConditions
```
public boolean allowGlobalConditions()
```
    从类复制的说明: 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.
    
    指定者:
    
    allowGlobalConditions 在类中 Query
    
    返回:
    
    true if adding global conditions is allowed
  - getSortOrder
```
public SortOrder getSortOrder()
```
  - getParentSelect
```
public Select getParentSelect()
```
    Returns parent select, or null.
    
    返回:
    
    parent select, or null
  - isConstantQuery
```
public boolean isConstantQuery()
```
    从类复制的说明: Query
    
    Check if this query will always return the same value and has no side effects.
    
    覆盖:
    
    isConstantQuery 在类中 Query
    
    返回:
    
    if this query will always return the same value and has no side effects.
  - getIfSingleRow
```
public Expression getIfSingleRow()
```
    从类复制的说明: Query
    
    If this query is determined as a single-row query, returns a replacement expression.
    
    覆盖:
    
    getIfSingleRow 在类中 Query
    
    返回:
    
    the expression, or null

类 Select

字段概要

从类继承的字段 org.h2.command.Prepared

构造器概要

方法概要

从类继承的方法 org.h2.command.query.Query

从类继承的方法 org.h2.command.Prepared

从类继承的方法 java.lang.Object

构造器详细资料

Select

方法详细资料

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