In the Read From DB stage, while defining the query, you can include variables instead of actual column names. Using variables in the query allows you to customize the query conditions at runtime (using the Dataflow Options) or through the Job Executor .
However, you can also provide Stage Options value in the Runtime tab and view the schema and sample of records to be fetched by the query by using the Regenerate Fields and Preview buttons respectively.
A variable is defined using the format #{variable}, and inserted in either the
select or where clause of an SQL query.Note: You can edit a
query generated using the Visual Query Builder to include variables.
However, the edited query will not be readable by the Visual Query Builder anymore. The
Build SQL button is disabled when you include a variable in a manually
written or generated SQL query.