- Tuple
- Definition: A tuple represents a single row in a relational table. It is an ordered set of values corresponding to attributes of an entity.
- Characteristics:
- Each tuple is unique within a table (enforced by primary keys).
- Represents a specific instance of an entity or relationship.
- Example: In a
Student table, a tuple could be:
(101, 'Alice', 'CS', 21).
- Field
- Definition: A field represents a single cell in a table, corresponding to the intersection of a row (tuple) and a column (attribute).
- Characteristics:
- Contains a single piece of data.
- The value in a field is derived from the domain of its attribute.
- Example: In a
Student table, the Name field for one tuple may contain 'Alice'.
- Domain
- Definition: A domain is the set of permissible values for an attribute. It defines constraints on the type, format, and range of values an attribute can hold.
- Characteristics:
- Ensures data validity and integrity.
- Shared domains can enforce consistency across tables.
- Example:
- Domain of
Age: Integer values between 0 and 120.
- Domain of
Email: Strings matching an email format.