[Inoformatica] Source Qualifier Transformation

Source Qualifier Transformation

::Transformation type::

Source Qualifier extracts rows from the Source Relational table to Flat file. When adding a source to a mapping, The Designer automatically adds Source Qualifier to the mapping.
One curious question arises in the mind that why do we need a separate transformation for extracting rows from a Source? Cants we extract rows directly from a Source? The following are the main  reason for use of Source Qualifier:
- To filter out the rows based on some condition. This can be done in Source Filter option.
- To select distinct rows from the Source. This can be done by selecting Select Distinct option. This makes the Source Qualifier a Active transformation.
- Performing joins while extracting data from Source.
- Assigning a SQL over-ride query to limit the number of rows extracted.

   By default, the Source Qualifier extracts ALL rows from the Source unless any one of the condition is checked
In case of having multiple pipe-lines in the mapping, one can specify the Target Load Order based on the Source Qualifier.
The Source Qualifier by default generates the SQL query that it uses to extract the data from Source. One can have all the columns from the Source connected to the Source Qualifier. Also, only the required columns can be connected further to next transformation. It is noteworthy that only the columns that are output from the Source Qualifier appear in the SQL Query.

::Over-riding the Source Qualifier Query::
- To limit the number of rows and specify a custom query, one can over-ride the default SQL query in the Source Qualifier.
- One must be cautious while over-riding the default query. The sequencing of the columns in the over-ride must exactly match the sequencing in default SQL query, otherwise the session fails.
- Also, ensure to validate the query by clicking on Validate button.

The following example shows the use of Source Qualifier Transformation to extract data where Salary > 10000.