Records, fields and stored types

A table has one row for each asset and separate columns for Copies and Loan days. To find Loan days for asset D19, which labels must you use?

A row and a column together identify the requested value

One record, several fields

In this single-table model, a record is one row of related values about one asset

A field is a named attribute, shown as a column. Asset code, Copies and Loan days are three different fields

A field value is one stored entry, such as the Copies value 2 in the A07 record. The header labels are not another asset record

These are synthetic asset records

Find a row-column intersection

This synthetic asset table contains one record per asset code. Copies and Loan days are separate fields; the header row is not an asset record

What is the Loan days value for asset B12?

Find the record whose Asset code is B12

In that row, the Loan days field contains 14; values in other rows or columns answer different questions

Keep the requested field

Keep asset A07 selected and compare Copies with Loan days. Then keep Loan days selected and change to asset D19. Predict each value from the table before checking the readout

With asset D19 and Loan days selected, what does the displayed value 10 mean?

A table has the three fields Asset code, Copies and Loan days, with four asset rows underneath its single header row. How many records and fields does it contain?

Records are asset rows; fields are the named attributes

Use the field's meaning and storage rule

These classroom tasks use three storage conventions: Text for preserved labels, Whole number for numerical counts, and Boolean for the two logical states true and false

A value containing digits is not automatically a quantity. The label 0042 may need all four characters, while a count of 42 means forty-two items

This is about the declared storage type and intended operations, not the statistical labels nominal, ordinal, discrete or continuous

Real systems support other types and conversion rules. Apply the conventions stated in each task rather than assuming that every tool stores values in the same way

An identifier is not a count

Use these classroom storage conventions: Text preserves labels and their characters, Whole number stores counts used numerically, and Boolean stores the two logical states true and false

An asset code contains letters and digits, such as A07, and must preserve them as a label

Which type matches the stated convention for this field?

The label contains letters as well as digits; it is not a count or a two-state flag

Under the supplied conventions, choose Text

Preserve an exact label

Store a count for arithmetic

Use these classroom storage conventions: Text preserves labels and their characters, Whole number stores counts used numerically, and Boolean stores the two logical states true and false

Copies available is a count of items: 0, 1, 2 and so on; the system adds these counts

Which type matches the stated convention for this field?

Items are counted in whole units, and adding the values is meaningful

Under the supplied conventions, choose Whole number

A numerical count of days

A Boolean stores one of two logical states

A Boolean flag stores true or false for a stated condition, such as whether an item has been inspected

A Returned flag is different from a Copies returned count: one gives a truth state, the other gives a numerical quantity

A field's type limits the kind of value it stores. Further validation rules, such as an allowed range, are a separate next step

A flag or a count?

Collect fields for a stated purpose

Before adding a field, state what the solution needs to do with it

For a report of total loans by asset category, category and loan-count data can support the report without collecting borrowers' home addresses

Whether a field is essential depends on the actual purpose. A different task, such as arranging a delivery, has different requirements

An anonymous activity survey only needs to count how many votes each activity receives. It will not contact anyone or match votes to individuals. Which proposed data is needed for this stated report?

Match each proposed field to the report and its explicit exclusions

Structure, meaning and purpose

A record is a related row of values; a field is one named attribute

Use both the record and field labels to locate a value

Apply the declared type convention to distinguish identifiers, numerical counts and Boolean flags

Choose fields that serve the stated purpose; do not collect unrelated personal data by default