com.orientechnologies.orient.core.sql.functions.misc

Class OSQLFunctionCount

java.lang.Object

com.orientechnologies.orient.core.sql.functions.OSQLFunctionAbstract

com.orientechnologies.orient.core.sql.functions.OSQLFunctionConfigurableAbstract

com.orientechnologies.orient.core.sql.functions.math.OSQLFunctionMathAbstract

com.orientechnologies.orient.core.sql.functions.misc.OSQLFunctionCount

All Implemented Interfaces:

OSQLFunction

public class OSQLFunctionCount
extends OSQLFunctionMathAbstract

Count the record that contains a field. Use * to indicate the record instead of the field. Uses the context to save the counter number. When different Number class are used, take the class with most precision.

Author:

Luca Garulli (l.garulli--(at)--orientdb.com)

Field Summary

Fields

Modifier and Type	Field and Description
static String	NAME

Fields inherited from class com.orientechnologies.orient.core.sql.functions.OSQLFunctionConfigurableAbstract

configuredParameters

Fields inherited from class com.orientechnologies.orient.core.sql.functions.OSQLFunctionAbstract

maxParams, minParams, name

Constructor Summary

Constructors

Constructor and Description
OSQLFunctionCount()

Method Summary

Modifier and Type	Method and Description
boolean	aggregateResults() A function can make calculation on several records before returning a result.
Object	execute(Object iThis, OIdentifiable iCurrentRecord, Object iCurrentResult, Object[] iParams, OCommandContext iContext) Process a record.
Object	getResult() Only called when function aggregates results after all records have been passed to the function.
String	getSyntax() Returns a convenient SQL String representation of the function.
Object	mergeDistributedResult(List<Object> resultsToMerge) This method correspond to distributed query execution
void	setResult(Object iResult) Called by OCommandExecutor, given parameter is the number of results.

Methods inherited from class com.orientechnologies.orient.core.sql.functions.math.OSQLFunctionMathAbstract

getClassWithMorePrecision, getContextValue, shouldMergeDistributedResult

Methods inherited from class com.orientechnologies.orient.core.sql.functions.OSQLFunctionConfigurableAbstract

config, toString

Methods inherited from class com.orientechnologies.orient.core.sql.functions.OSQLFunctionAbstract

filterResult, getDistributedStorageId, getMaxParams, getMinParams, getName, getSingleItem, getSingleProperty, returnDistributedResult

Methods inherited from class java.lang.Object

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

Field Detail

NAME

public static final String NAME

See Also:

Constant Field Values

Constructor Detail

OSQLFunctionCount

public OSQLFunctionCount()

Method Detail

execute

public Object execute(Object iThis,
                      OIdentifiable iCurrentRecord,
                      Object iCurrentResult,
                      Object[] iParams,
                      OCommandContext iContext)

Description copied from interface: OSQLFunction

Process a record.

iCurrentRecord - : current record

iCurrentResult - TODO

iParams - : function parameters, number is ensured to be within minParams and maxParams.

iContext - : object calling this function

Returns:

function result, can be null. Special cases : can be null if function aggregate results, can be null if function filter results : this mean result is excluded

aggregateResults

public boolean aggregateResults()

Description copied from interface: OSQLFunction

A function can make calculation on several records before returning a result.

Example of such function : sum, count, max, min ...

The final result of the aggregation is obtain by calling OSQLFunction.getResult()

Specified by:

aggregateResults in interface OSQLFunction

Overrides:

aggregateResults in class OSQLFunctionMathAbstract

Returns:

true if function aggregate results

getSyntax

public String getSyntax()

Description copied from interface: OSQLFunction

Returns a convenient SQL String representation of the function.

Example :

  myFunction( param1, param2, [optionalParam3])
 

This text will be used in exception messages.

Returns:

String , never null.

getResult

public Object getResult()

Description copied from interface: OSQLFunction

Only called when function aggregates results after all records have been passed to the function.

Specified by:

getResult in interface OSQLFunction

Overrides:

getResult in class OSQLFunctionAbstract

Returns:

Aggregation result

setResult

public void setResult(Object iResult)

Description copied from interface: OSQLFunction

Called by OCommandExecutor, given parameter is the number of results. ??? strange ???

Specified by:

setResult in interface OSQLFunction

Overrides:

setResult in class OSQLFunctionAbstract

mergeDistributedResult

public Object mergeDistributedResult(List<Object> resultsToMerge)

Description copied from interface: OSQLFunction

This method correspond to distributed query execution

Specified by:

mergeDistributedResult in interface OSQLFunction

Overrides:

mergeDistributedResult in class OSQLFunctionAbstract

Parameters:

resultsToMerge - is the results that comes from different nodes

Returns:

is the valid merged result