Boolean
A data type with two possible values, true and false. A column such as subscribed or is_active is Boolean in meaning, whatever is typed into it.
In real files the two values arrive as Yes and No, Y and N, 1 and 0, TRUE and false, and a checkmark. A blank is a third state, unknown, and should not be read as false without a reason.
Where it comes up
- Yes and no in many formsA column that should hold only yes or no holds Y, yes, TRUE, 1, and several other ways of saying the same two things.
- True blanksA cell is really empty, and the file does not say whether the value is unknown, not applicable, or was never asked for.
See also
- Data typeThe kind of value a column holds, such as text, whole number, decimal, date, or true and false. The type decides what operations make sense.
- Categorical dataValues that place each row in one of a limited set of groups, such as a status of open, pending, or closed. The values are labels, not quantities.
- NullThe explicit marker a database or file uses for no value. It is different from zero, from an empty string, and from the text NULL typed into a cell.