Migrating Data to an Integrated Database - High-Performance Web Databases: Design, Development, and Deployment - page 603

Exhibit 42-2. Mapping specific data elements to general data elements.
Inconsistent Coding Structures
The values used to represent information may differ between two data
items. As illustrated in Exhibit 3, the source data element may use “S” for
single and “M” for married, and the target data element may use “1” for sin-
gle and “2” for married. In this case, mapping between the two coding
structures is straightforward.
In some cases, one coding structure is more specific than another. For
example, the source data element uses “U” for undergraduate and “G” for
graduate and the target data element uses four different codes (“F” for Fresh-
man, “S” for Sophomore, “J” for Junior, and “R” for Senior) for undergradu-
ates, and two codes (“M” for Masters and “P” for PhD) for graduate students.
Retaining the more specific coding structures is recommended. As the map-
pings in Exhibit 4 illustrate, additional information is necessary to map the
general codes — G and U — to the specific codes — F, S, J, R, M, and P.
Exhibit 42-3. Mapping between different codes.