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Yellowfin offers a way to save your transformed data into a database table via the SQL database output step. To configure this step, you will need to configure a number of different settings in relation to the target database, target table, the type of update that is required, and the fields that will be mapped. This guide explains how to do all of this.


Warning: Extra caution should be taken when configuring the output step so that any existing source data does not get accidentally overwritten. The output to database step has a variety of options such as dropping tables, truncating (deleting) data, adding new rows, and updating existing data. It is recommended that a test database is used when developing transformation flows. Further, the output step is disabled by default when in edit mode (see Run in Design mode option).



Understanding the Options

Table Creation Options

Table Creation Type


Use Existing

With this selection, the data will be written into an existing table that you select.

Create If Not Exists

If the specified table doesn’t exist in the database, then create a new one, but if it does (or once it has been created) save content into it.

Drop Existing

Always delete the existing table and create a new one. Only use this option when you know that the old data does not need to be retained.

Drop If Metadata Conflict

If there is a metadata conflict between the data in the flow and the table (such a conflict could refer to different number of fields/columns in the flow file than in the table or possibly a different data type), then delete the table and create a new one to store data; otherwise if the metadata matches without there being a conflict, use the existing table. Only use this option when you know that the old data does not need to be retained.

For most users, it is expected that the Use Existing option will be used most often. The database administrator will create the tables that will be the target for the transformations, and assign the relevant security access.

In rarer circumstances, the target tables may not exist in advance. In these cases Yellowfin can create the table for you, provided you have the right security access. The Create if Not Exists option will create the table if it does not exist. Typically this will only happen the first time a flow is run, after which the existing table will be used. The Drop Existing will always delete and re-create the table, thus deleting any data that may have been stored in that table - and should be used with caution. Similarly the Drop if Meta-Data Conflict will drop and re-create the table if there is a mismatch between the table structure and the data contained in the flow. This option is also destructive to data and should be used with caution.




Update Type

Update Type



To append or add data to the end of the existing data.


To replace all the existing data with the new values. This should be used with caution as it will delete any existing data.


Update the value of fields in the database table where a matching row exists in the transformation flow. This option overwrites existing data and should be used with caution.

Update & Insert

Update the value of fields in the database table where a matching row exists in the transformation flow. This option overwrites existing data and should be used with caution. If no matching row exists then insert a new row.



Step Configuration

Once you are ready to store your transformed data into an SQL output step, follow the instructions below:


  1. Click on the Output Steps button on the left side of the Transformation Flow builder, to view a list of output steps.
  2. Drag the Output to SQL Database step from the list. 

  3. Click on the step to bring up in configuration details in the Transformation Flow panel.
  4. Then select a database from the list. Only writeable data sources will be shown.
  5. Choose a table creation option. Click here to understand the table creation options.

  6. Continue with the selected process:
    1. If Use Existing was selected, select a pre-existing table to write data into. 

    2. If Create If Not Exists was selected, then enter a new table name. You can optionally select any table fields that you would like to index (note: indexes are used to improve query performance. If in doubt about this option, please contact your system administrator). 

    3. If Drop Existing was selected, then enter a new table name. Choose any field to index it, if required. (Then skip the next 2 steps of this guide.)
    4. If Drop if Metadata Conflicts was selected, then enter a new table name, also specify whether the existing table is to be dropped in case there are more fields in the transformation flow than in the table.  

  7. Choose an update type to indicate how the existing table will be updated. Click here to understand all the options.

  8. For Update and Update & Insert options, additional row matching is required. This is done by configuring a Where clause to specify which fields should be updated.

    When updating existing records in the output database, you will need to specify two types of columns/fields:

    • A join field: This is a field that joins the flow table with the database table. This field should contain matching values in both the tables. The join option is used with this field.

    • A set field: This is a field whose value will be used to update the database.  The set option is used with this field.

    If no option is selected, the field will not be used in the join or be updated as part of the flow. 

    1. Choose the Join option for this column.

    2. Then select the field with which to update the output database, and choose the Set option with it (this ensure that the database column will be replaced with the values of this field).

  9. Switch on the Run in design mode toggle to run this output step in design mode. SEE WARNING NOTE.

  10. Once the configuration is done, click on the Apply button to save these changes.




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