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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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Independent Practice: Design fields
Independent Practice: Design fields
- A postal code may contain letters and leading zeroes. Choose TEXT or INTEGER: [Space 1]
- A whole number of borrowed books uses INTEGER or BOOLEAN? [Space 2]
- A paid/not-paid flag uses BOOLEAN or TEXT? [Space 3]
Interactive exercises for Module 2 and beyond require an active plan.