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Common exam pitfall
Students often choose Number/Integer for telephone numbers, forgetting that leading zeros are dropped by numeric types.
A table holds records of the same kind. A record is one row; a field is a named category of information represented by a column. Consistent field names and appropriate types make data easier to query and validate.
Worked single-table design
A lending club needs MemberID, Name, PostalCode, BooksBorrowed and FeesPaid. MemberID identifies one record. Name and PostalCode use text: a postal code can contain letters and leading zeroes, so it is not a quantity for arithmetic. BooksBorrowed is an integer. FeesPaid is Boolean.
Other useful types include real for fractional numbers, date/time for dates or times, and character for a single character. Select types according to use, not just whether a sample contains digits.
Independent design
Design a single table for equipment loans, with one record per loan. Choose fields for the borrower, item, loan date and return status. Name a unique key and justify each type. A well-designed relational database can reduce duplication; it does not automatically eliminate duplicate facts or update problems.
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Exam-Style Check: Selecting Appropriate Database Field Data Types
• Multiple ChoiceA database administrator is designing a patient table for a medical clinic. The table includes a field for the patient's mobile telephone number (e.g., "07123456789").
Which data type should be selected for the TelephoneNumber field, and what is the primary technical rationale?
Interactive exercises for Module 2 and beyond require an active plan.