Page 23 - Database-En-V3

6. Set up table relationships according to the linking of data together

Review each table and determine how the data in one table relates to the data in the
other tables. To represent these relationships, add fields to the tables (known as a
foreign key) or create new tables to clarify the relationships as needed. The types of
relationships will be explained later.

7. Review the entire database

When you obtain the tables, fields, and relationships, you must create and fill your
own tables with typical data and attempt to retrieve the data and infer information by
creating queries. You also may add new records and modify previous data as a
simulation of applications and programs that used databases in its services. Create
drafts of forms and reports and see if they display the expected data. Look for
duplication of unnecessary data, then, modify the design to eliminate it.

This helps you identify potential problems. For example, you may need to add a
column that you forgot during the design phase, or you may have a table that needs
to be split into two tables to remove duplicates.

Here are some things to check:

✓ Did you forget any columns? If so, does the data belong in existing tables? If
the data is about something else, you may need to create another table.
Create a column for each statement you need to retrieve or use. If you can't
infer information from other columns, you'll probably need to add a new
column for them.

✓ Are any columns unnecessary because they can be calculated from existing
fields? If the information item can be calculated from other existing columns,
delete it. For example, the total degrees of courses this semester is calculated
and added in column, delete it. Where, it is recommended to just store the
courses' degrees and avoid creating a new column for its summation (total).

✓ Do you frequently enter duplicate data into a table? If so, you may need to split
the table into two tables that have a one-to-many relationship.

✓ Do you have tables that contain many fields, a specific number of records with
empty values? If so, you should redesign the table to include more records,
fewer fields and without null values as possible.

✓ Is each data element broken down into smaller, useful parts? If you need to
report, sort, find, or calculate a data item, place these items in its own column.

✓ Does each column contain a fact about the table title? If a column does not
include a statement about the table title, it may belong to another table.

16 Training unit in the field of technological information - at the Supreme Council of Universities © Intellectual property rights 2024