Data transformation

In computing, a data transformation converts a set of data values from the data format of a source data system into the data format of a destination data system. It is often used in a data warehouse system.

Data transformation can be divided into two steps:

Data element to data element mapping is frequently complicated by complex transformations that require one-to-many and many-to-one transformation rules.

The code generation step takes the data element mapping specification and creates an executable program that can be run on a computer system. Code generation can also create transformation in easy-to-maintain computer languages such as Java or XSLT.

A master data recast is another form of data transformation where the entire database of data values is transformed or recast without extracting the data from the database. All data in a well designed database is directly or indirectly related to a limited set of master database tables by a network of foreign key constraints. Each foreign key constraint is dependent upon a unique database index from the parent database table. Therefore, when the proper master database table is recast with a different unique index, the directly and indirectly related data are also recast or restated. The directly and indirectly related data may also still be viewed in the original form since the original unique index still exists with the master data. Also, the database recast must be done in such a way as to not impact the applications architecture software.

When the data mapping is indirect via a mediating data model, the process is also called data mediation.

There are numerous languages available for performing data transformation. Many transformation languages require a grammar to be provided. In many cases the grammar is structured using something closely resembling Backus–Naur Form (BNF). There are numerous languages available for such purposes varying in their accessibility (cost) and general usefulness. Examples of such languages include:

...
Wikipedia