Skip to main contentPrequel Import anticipates the case where Source Dataset schemas do not perfectly match target Destination schemas without some mapping and transformation. To support bridging between the two, Prequel supports a number of mapping and transformation options.
Prequel Import provides tooling to support both the Destination owner (you) to perform the mapping, as well as to expose this experience to your users. If you plan to embed this experience for your customers, please see the Customer Experience guide.
Custom queries
At a full table level, custom SQL queries can be used to transform the Source data. This is a good solution for users that are comfortable with SQL, or who need to leverage aggregations or logic that stretches across different rows.
Column mapping
At the row (or “per record”) level, Source columns can be mapped to the target Destination field.
Transformations of single or multiple columns can also be defined and mapped to target Destination fields. For example, a Source may have 2 columns — first_name, last_name — and the target Destination may ask for a full_name field. A concatenation of CONCATENATE(first_name, ” ”, last_name) can be used to transform the Source fields into the expected target shape. 
