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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.If you are interested in merging spatial data,see theMerging or Joining Spatial Dataarticle.
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 theCombining Multiple Streams of Data (Append vs.Merge or Join)article.
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,seethe documentation.
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) Is all of my data already inside the workspace?
如果是:遵循内部路径
If no: Follow the EXTERNAL path
2) Does the FeatureJoiner for internal or DatabaseJoiner for external work for my data?
If yes: Great!End here
If no: Continue to question 3
3) Do I know or want to use SQL?
If yes: See the transformers in the green SQL box
If no: See the transformers in the blue No SQL box
4) Did any of those transformers work?
If yes: Great!
If no: Read the documentation to ensure if it was set up correctly and suites your needs
If unsure: Re-read the documentation,if still unsure ask aquestion in our 亚搏国际在线官网community.
Transformers listed in alphabetical order:
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 DatabaseJoiner Transformer tutorial
Join CSV File to a Database Table with the DatabaseJoiner
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.*Note this transformer only works for FME 2018+
The FeatureJoiner Transformer tutorial
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.
The FeatureMerger Transformer tutorial
Combining Multiple Streams of Data (Append vs.Merge or Join)
Polling Places for Local Government
The FeatureReader reads features from any FME-supported format.This can be done midstream which aids in adding and joining data quickly.
The FeatureReader Transformer tutorial
Performing spatial queries on database tables using the FeatureReader
The InlineQuerier utilizes the power of SQL.It can be used to build data linkages more directly by making use of a temporary database consisting of tables created from incoming features and returning the results (generated from SQL statements) as new features.
The InlineQuerier Transformer tutorial
Using the InlineQuerier as a replacement for multiple FeatureMergers
The SQLExecutor and SQLCreator transformers are very similar.They are both used to execute SQL against a database.The only difference is that the SQLExecutor requires an incoming feature to trigger the SQL statement,and the SQLCreator does not.
The SQLExecutor and SQLCreator Transformers tutorial
Using the SQLExecutor to do a SQL Join
Performing native spatial queries on database tables using the SQLExecutor
Looking for spatial joining transformers?See theMerging or Joining Spatial Dataarticle.
Using the FeatureWriter Transformer with your Database
Using the SQLExecutor to do a SQL Join
Performing native spatial queries on database tables using the SQLExecutor
Using the SQLExecutor or SQLCreator to issue commands to a database
Performing spatial queries on database tables using the FeatureReader
Executing a Stored Procedure on Microsoft SQL Server with FME
Using the InlineQuerier as a replacement for multiple FeatureMergers
Splitting SQL statements using the FME_SQL_DELIMITER directive
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