Pre SQL: The SQL query fires initially when loading to that database.
Example for Pre SQL: Suppose my requirement is to load the records daily. If some updates I have to reload the records for that particular day. In that case I will write a pre-SQL so that when ever I run first it will delete the records from the database and reload the latest records.
Post SQL: The
SQL query fires at the end i.e. after loading the records to the database.
Example for Post SQL: In a case that I have to delete the records for a particular day once the entire ODS load finishes the stage records has to be deleted. In such cases I will write a post
SQL to delete the stage records once it loads to ODS.