Aggregate (H2 Database Engine 2.0.0 API)

java.lang.Object
- org.h2.expression.Expression
- - org.h2.expression.analysis.DataAnalysisOperation
  - - org.h2.expression.aggregate.AbstractAggregate
    - - org.h2.expression.aggregate.Aggregate

所有已实现的接口:

ExpressionWithFlags, HasSQL, Typed
```
public class Aggregate
extends AbstractAggregate
implements ExpressionWithFlags
```
Implements the integrated aggregate functions, such as COUNT, MAX, SUM.

字段概要
- 从类继承的字段 org.h2.expression.aggregate.AbstractAggregate
  args, distinct, filterCondition, type
- 从类继承的字段 org.h2.expression.analysis.DataAnalysisOperation
  over, overOrderBySort, select, STAGE_GROUP, STAGE_RESET, STAGE_WINDOW
- 从类继承的字段 org.h2.expression.Expression
  AUTO_PARENTHESES, MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL, WITH_PARENTHESES, WITHOUT_PARENTHESES
- 从接口继承的字段 org.h2.util.HasSQL
  ADD_PLAN_INFORMATION, DEFAULT_SQL_FLAGS, NO_CASTS, QUOTE_ONLY_WHEN_REQUIRED, REPLACE_LOBS_FOR_TRACE, TRACE_SQL_FLAGS

构造器概要

构造器
构造器和说明

Aggregate(AggregateType aggregateType, Expression[] args, Select select, boolean distinct)
Create a new aggregate object.

构造器
构造器和说明
`Aggregate(AggregateType aggregateType, Expression[] args, Select select, boolean distinct)` Create a new aggregate object.

方法概要

所有方法静态方法实例方法具体方法
限定符和类型	方法和说明
`protected Object`	`createAggregateData()` Create aggregate data object specific to the subclass.
`Value`	`getAggregatedValue(SessionLocal session, Object aggregateData)` Returns aggregated value.
`AggregateType`	`getAggregateType()` Returns the type of this aggregate.
`static AggregateType`	`getAggregateType(String name)` Get the aggregate type for this name, or -1 if no aggregate has been found.
`int`	`getCost()` Estimate the cost to process the expression.
`Object`	`getExtraArguments()` Returns the additional arguments.
`int`	`getFlags()` Returns the flags.
`protected int`	`getNumExpressions()` Returns the number of expressions, excluding OVER clause.
`Select`	`getSelect()` Returns the select statement.
`StringBuilder`	`getUnenclosedSQL(StringBuilder builder, int sqlFlags)` Get the SQL statement of this expression.
`Value`	`getValue(SessionLocal session)` Return the resulting value for the current row.
`boolean`	`isDistinct()` Returns if distinct is used.
`boolean`	`isEverything(ExpressionVisitor visitor)` Check if this expression and all sub-expressions can fulfill a criteria.
`void`	`mapColumnsAnalysis(ColumnResolver resolver, int level, int innerState)` Map the columns of the resolver to expression columns.
`Expression`	`optimize(SessionLocal session)` Try to optimize the expression.
`protected void`	`rememberExpressions(SessionLocal session, Value[] array)` Stores current values of expressions into the specified array.
`void`	`setEvaluatable(TableFilter tableFilter, boolean b)` Tell the expression columns whether the table filter can return values now.
`void`	`setExtraArguments(Object extraArguments)` Sets the additional arguments.
`void`	`setFlags(int flags)` Set the flags for this expression.
`void`	`setOrderByList(ArrayList<QueryOrderBy> orderByList)` Set the order for ARRAY_AGG() or GROUP_CONCAT() aggregate.
`protected void`	`updateAggregate(SessionLocal session, Object aggregateData)` Updates an aggregate value.
`protected void`	`updateFromExpressions(SessionLocal session, Object aggregateData, Value[] array)` Updates the provided aggregate data from the remembered expressions.
`protected void`	`updateGroupAggregates(SessionLocal session, int stage)` Invoked when processing group stage of grouped window queries to update arguments of this aggregate.

从类继承的方法 org.h2.expression.aggregate.AbstractAggregate
appendTailConditions, getFilterCondition, getOrderedResultLoop, getSubexpression, getSubexpressionCount, getType, isAggregate, setFilterCondition, updateAggregate

从类继承的方法 org.h2.expression.analysis.DataAnalysisOperation
createOrder, getGroupData, getOverCondition, getOverOrderBySort, getWindowData, mapColumns, setOverCondition, updateAggregate, updateOrderedAggregate

从类继承的方法 org.h2.expression.Expression
addFilterConditions, createIndexConditions, getAlias, getBooleanValue, getColumnName, getColumnNameForView, getEnclosedSQL, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getTableAlias, getTableName, getWhenSQL, getWhenValue, isConstant, isIdentity, isNullConstant, isValueSet, isWhenConditionOperand, needParentheses, optimizeCondition, toString, writeExpressions, writeExpressions

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

从接口继承的方法 org.h2.util.HasSQL
getTraceSQL

- 构造器详细资料
  - Aggregate
```
public Aggregate(AggregateType aggregateType,
                 Expression[] args,
                 Select select,
                 boolean distinct)
```
    Create a new aggregate object.
    
    参数:
    
    aggregateType - the aggregate type
    
    args - the aggregated expressions
    
    select - the select statement
    
    distinct - if distinct is used
- 方法详细资料
  - getAggregateType
```
public static AggregateType getAggregateType(String name)
```
    Get the aggregate type for this name, or -1 if no aggregate has been found.
    
    参数:
    
    name - the aggregate function name
    
    返回:
    
    null if no aggregate function has been found, or the aggregate type
  - setOrderByList
```
public void setOrderByList(ArrayList<QueryOrderBy> orderByList)
```
    Set the order for ARRAY_AGG() or GROUP_CONCAT() aggregate.
    
    参数:
    
    orderByList - the order by list
  - getAggregateType
```
public AggregateType getAggregateType()
```
    Returns the type of this aggregate.
    
    返回:
    
    the type of this aggregate
  - setExtraArguments
```
public void setExtraArguments(Object extraArguments)
```
    Sets the additional arguments.
    
    参数:
    
    extraArguments - the additional arguments
  - getExtraArguments
```
public Object getExtraArguments()
```
    Returns the additional arguments.
    
    返回:
    
    the additional arguments
  - setFlags
```
public void setFlags(int flags)
```
    从接口复制的说明: ExpressionWithFlags
    
    Set the flags for this expression.
    
    指定者:
    
    setFlags 在接口中 ExpressionWithFlags
    
    参数:
    
    flags - the flags to set
  - getFlags
```
public int getFlags()
```
    从接口复制的说明: ExpressionWithFlags
    
    Returns the flags.
    
    指定者:
    
    getFlags 在接口中 ExpressionWithFlags
    
    返回:
    
    the flags
  - updateAggregate
```
protected void updateAggregate(SessionLocal session,
                               Object aggregateData)
```
    从类复制的说明: AbstractAggregate
    
    Updates an aggregate value.
    
    指定者:
    
    updateAggregate 在类中 AbstractAggregate
    
    参数:
    
    session - the session
    
    aggregateData - aggregate data
  - updateGroupAggregates
```
protected void updateGroupAggregates(SessionLocal session,
                                     int stage)
```
    从类复制的说明: DataAnalysisOperation
    
    Invoked when processing group stage of grouped window queries to update arguments of this aggregate.
    
    覆盖:
    
    updateGroupAggregates 在类中 AbstractAggregate
    
    参数:
    
    session - the session
    
    stage - select stage
  - getNumExpressions
```
protected int getNumExpressions()
```
    从类复制的说明: DataAnalysisOperation
    
    Returns the number of expressions, excluding OVER clause.
    
    指定者:
    
    getNumExpressions 在类中 DataAnalysisOperation
    
    返回:
    
    the number of expressions
  - rememberExpressions
```
protected void rememberExpressions(SessionLocal session,
                                   Value[] array)
```
    从类复制的说明: DataAnalysisOperation
    
    Stores current values of expressions into the specified array.
    
    指定者:
    
    rememberExpressions 在类中 DataAnalysisOperation
    
    参数:
    
    session - the session
    
    array - array to store values of expressions
  - updateFromExpressions
```
protected void updateFromExpressions(SessionLocal session,
                                     Object aggregateData,
                                     Value[] array)
```
    从类复制的说明: AbstractAggregate
    
    Updates the provided aggregate data from the remembered expressions.
    
    指定者:
    
    updateFromExpressions 在类中 AbstractAggregate
    
    参数:
    
    session - the session
    
    aggregateData - aggregate data
    
    array - values of expressions
  - createAggregateData
```
protected Object createAggregateData()
```
    从类复制的说明: DataAnalysisOperation
    
    Create aggregate data object specific to the subclass.
    
    指定者:
    
    createAggregateData 在类中 DataAnalysisOperation
    
    返回:
    
    aggregate-specific data object.
  - getValue
```
public Value getValue(SessionLocal session)
```
    从类复制的说明: Expression
    
    Return the resulting value for the current row.
    
    覆盖:
    
    getValue 在类中 DataAnalysisOperation
    
    参数:
    
    session - the session
    
    返回:
    
    the result
  - getAggregatedValue
```
public Value getAggregatedValue(SessionLocal session,
                                Object aggregateData)
```
    从类复制的说明: DataAnalysisOperation
    
    Returns aggregated value.
    
    指定者:
    
    getAggregatedValue 在类中 DataAnalysisOperation
    
    参数:
    
    session - the session
    
    aggregateData - the aggregate data
    
    返回:
    
    aggregated value.
  - mapColumnsAnalysis
```
public void mapColumnsAnalysis(ColumnResolver resolver,
                               int level,
                               int innerState)
```
    从类复制的说明: DataAnalysisOperation
    
    Map the columns of the resolver to expression columns.
    
    覆盖:
    
    mapColumnsAnalysis 在类中 AbstractAggregate
    
    参数:
    
    resolver - the column resolver
    
    level - the subquery nesting level
    
    innerState - one of the Expression MAP_IN_* values
  - optimize
```
public Expression optimize(SessionLocal session)
```
    从类复制的说明: Expression
    
    Try to optimize the expression.
    
    覆盖:
    
    optimize 在类中 AbstractAggregate
    
    参数:
    
    session - the session
    
    返回:
    
    the optimized expression
  - setEvaluatable
```
public void setEvaluatable(TableFilter tableFilter,
                           boolean b)
```
    从类复制的说明: Expression
    
    Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.
    
    覆盖:
    
    setEvaluatable 在类中 AbstractAggregate
    
    参数:
    
    tableFilter - the table filter
    
    b - true if the table filter can return value
  - getUnenclosedSQL
```
public StringBuilder getUnenclosedSQL(StringBuilder builder,
                                      int sqlFlags)
```
    从类复制的说明: Expression
    
    Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are never appended.
    
    指定者:
    
    getUnenclosedSQL 在类中 Expression
    
    参数:
    
    builder - string builder
    
    sqlFlags - formatting flags
    
    返回:
    
    the specified string builder
  - isEverything
```
public boolean isEverything(ExpressionVisitor visitor)
```
    从类复制的说明: Expression
    
    Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.
    
    覆盖:
    
    isEverything 在类中 DataAnalysisOperation
    
    参数:
    
    visitor - the visitor
    
    返回:
    
    if the criteria can be fulfilled
  - getCost
```
public int getCost()
```
    从类复制的说明: Expression
    
    Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.
    
    指定者:
    
    getCost 在类中 Expression
    
    返回:
    
    the estimated cost
  - getSelect
```
public Select getSelect()
```
    Returns the select statement.
    
    返回:
    
    the select statement
  - isDistinct
```
public boolean isDistinct()
```
    Returns if distinct is used.
    
    返回:
    
    if distinct is used

类 Aggregate

字段概要

从类继承的字段 org.h2.expression.aggregate.AbstractAggregate

从类继承的字段 org.h2.expression.analysis.DataAnalysisOperation

从类继承的字段 org.h2.expression.Expression

从接口继承的字段 org.h2.util.HasSQL

构造器概要

方法概要

从类继承的方法 org.h2.expression.aggregate.AbstractAggregate

从类继承的方法 org.h2.expression.analysis.DataAnalysisOperation

从类继承的方法 org.h2.expression.Expression

从类继承的方法 java.lang.Object

从接口继承的方法 org.h2.util.HasSQL

构造器详细资料

Aggregate

方法详细资料

getAggregateType

setOrderByList

getAggregateType

setExtraArguments

getExtraArguments

setFlags

getFlags

updateAggregate

updateGroupAggregates

getNumExpressions

rememberExpressions

updateFromExpressions

createAggregateData

getValue

getAggregatedValue

mapColumnsAnalysis

optimize

setEvaluatable

getUnenclosedSQL

isEverything

getCost

getSelect

isDistinct