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of the set-at-a-time processing enabled by SQL. In addition, the use of a spe-
cific CASE-supported development methodology must be enforced.
The simultaneous use of multiple DBMSs
must be planned for when a parallel installation is to be adopted during the
conversion process. Policies and procedures necessary for the effective
coordination of two DBMSs must be established so that the integrity of the
databases is maintained and business is conducted as usual. This
enhances the success of the migration to a relational structure.
The Use of Multiple DBMSs.
Systems development professionals and end users must pre-
pare for relational technology by welcoming additional training. Systems
professionals should receive comprehensive training with an emphasis on
data concepts, CASE-driven systems development, and set-at-a-time pro-
gramming techniques. End users should learn the use of 4GL facilities for
generating reports and for retrieving information from a relational database.
Training.
FOUR STEPS OF RELATIONAL CONVERSION
To ensure better preparation for the conversion and to facilitate a
smooth transition, the conversion must be carefully planned. The rela-
tional conversion process can be simplified into four important steps:
• Converting databases.
• Converting programs.
• Training IS professionals and end users.
• Documenting procedures, operations, policies, methodologies, stan-
dards, and guidelines.
In general, the conversion process is not strictly sequential. Tasks per-
formed in each step can overlap. A nonsequential view of the conversion
process is shown in Exhibit 1.
The first step is to convert databases. A set of programs must be written
to read the old master file to the new relational tables. Tables that are
designed to store data about events or transactions are also created. The
objective is to establish relational databases that meet third normal form.
In this step, relational databases and old files (or nonrelated databases) are
maintained in parallel during the conversion steps.
The next step is to convert programs. Experienced programmers must
be assigned to develop a translator to enable existing nonrelational pro-
grams to access relational databases. Other programmers must be respon-
sible for the development of routines that enable the existing nonrelational
programs to access relational databases. For applications that are not con-
vertible using these methods, a total approach that redesigns and rewrites
entire programs to fit into a relational structure is required.
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