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有什么方法可以在不更新流中的空值的情况下更新 MySQL Db。如果我的输入数据流包含一些空值,则当前使用“data_empty”值指示该空值。那时,CEP 使用该值(“data_empty”)更新数据库。我的目标是在不更新空值的情况下更新其余内容。是否可以使用 siddhi 和 WSO2 CEP。

@Plan:name('DBUpdateExecutionPlan')
@Import('testStream:1.0.0')
define stream input (id string, param1 string, param2 string);

@Export('testOutStream:1.0.0')
define stream output (id string, param1 string, param2 string);

@from(eventtable = 'rdbms' , datasource.name = 'MYSQL' , table.name = 'cep')
define table cepTable (id string, param1 string, param2 string) ;

from input#window.time(0 sec)
select * 
update cepTable on id == cepTable.id;
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1 回答 1

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仅将非空(在您的场景中不是“data_empty”)值更新到数据库有点困难。然而,在 Siddhi 中,有一个名为 的函数ifThenElse(condition, value if true, value if false),可以在您的场景中使用。请参阅下面的示例执行计划,以了解有关使用ifThenElse()和表更新的想法(类似于您的用例)。

@Plan:name('IfThenElseExecutionPlan')

@Import('inputStream:1.0.0')
define stream dataIn (roomId int, roomType string, roomTemp float);

@Export('outputStream:1.0.0')
define stream dataOut (roomId int, roomType string, roomTemp float);

@From(eventtable='rdbms', datasource.name='cepdatabase', table.name='roomTable')
define table roomTable (roomId int, roomType string, roomTemp float);

from dataIn[not((roomTable.roomId == roomId) in roomTable)]
insert into updateStream;

from dataIn join roomTable
on roomTable.roomId == dataIn.roomId
select  dataIn.roomId as roomId, 
        ifThenElse(dataIn.roomType=='data_empty', roomTable.roomType, dataIn.roomType) as roomType, 
        ifThenElse(dataIn.roomTemp==0.0f, roomTable.roomTemp, dataIn.roomTemp) as roomTemp
insert into updateStream;

from updateStream
insert overwrite roomTable
on roomTable.roomId == roomId;
于 2016-04-29T17:22:54.590 回答