span8
span4
span8
span4
Merging or joining data together in FME is accomplished by using a transformer.These transformers allow the user to define a relationship for the basis of a join.This article covers which transformers work best for merging data that comes from a spreadsheet or database.如果你有兴趣在合并空间数据,请参见合并或加入空间数据文章。
Merging or joining data together is different from connecting data streams in FME.When the data is merged the attributes from each dataset are combined together based on a common identifier and then output as a single fused dataset.When the data streams are just connected by drawing two connections to an input port of a transformer that isn’t a merging transformer, the data will be in a single stream, but the attributes will still be separate.For more information on combining data streams see the结合多个数据流(追加对合并或加入)文章。
There are two main categories for merging or joining transformers, they are: SQL and no-SQL.The transformers that are in the SQL category require knowledge of SQL;these are the InlineQuerier, SQLCreator, and the SQLExecutor.The no-SQL transformers have the same functionality of the SQL ones but can be set up easily without any database knowledge;these are the FeatureJoiner, FeatureMerger, FeatureReader, and the DatabaseJoiner.This isn’t an exhaustive list, there are other transformers that allow data to be joined but are used for a specific task.For more information on these other transformers, see文档。
Now when trying to decide which transformer is the correct one to use, follow the flowchart below to help.When trying to decide, inspect your data and ask the following questions:
1)我所有的数据已经是里面的工作空间?
如果是的话:按照内部路径
如果没有:按照外部路径
2)是否FeatureJoiner内部或DatabaseJoiner为我的数据的外部工作?
如果是的话:太好了!在这里结束
如果没有:继续问题3
3)我知道还是要使用SQL?
如果是的话:见变压器在绿色SQL箱
如果没有:见变压器的蓝色无SQL箱
4)没有做过这些变压器的工作?
如果是的话:太好了!
如果没有:阅读文档,以确保如果它被设置正确和符合您需求
如果不确定:重新阅读文档,如果仍然不确定问在我们的社会问题。亚搏国际在线官网
按字母顺序列出变形金刚:
The DatabaseJoiner, previously known as the Joiner transformer provides the ability to form a join against a database or other external dataset with an existing dataset in the workspace.
The FeatureJoiner transformer is a simpler version of the FeatureMerger and uses joins based on SQL, with greater performance.This transformer can be used with ease without prior SQL knowledge.*注意:该变压器仅适用于FME 2018+
The FeatueMerger performs a simple, in memory, join.The join is carried out from two or more input streams of data that have already been read using a reader or a transformer like the FeatureReader.
该FeatureReader读取任何FME支持的格式功能。这是可以做到的中游这有助于增加和快速连接数据。
该InlineQuerier利用SQL的功能。它可以更直接地通过利用由来自呼入功能创建的表的一个临时数据库的并返回结果(从SQL语句生成的)作为新的功能被用于生成数据的联系。
使用InlineQuerier为多个FeatureMergers更换
该SQLExecutor和SQLCreator变压器非常相似。它们都用于执行SQL对数据库。唯一的区别是,SQLExecutor需要进入的功能触发的SQL语句,以及SQLCreator没有。
寻找空间连接变压器?查看合并或加入空间数据文章。
© 2020 Safe Software Inc |Legal