In order to figure out how the data needs to be formatted, or mapped, it is essential to build a data mapping document. The data mapping document must include specifically the source and target data mappings. It must also include the primary key of all tables in source system.
Data mapping simply means matching of data. It is needed in order to save correct results from source to a target system.
We must have to implement the correct order of mapping in between data so as to avoid any errors or bad data insertion into the system.