Data Integrity Rules to Know for Intro to Database Systems

Data integrity rules are essential for maintaining accurate and reliable information in databases. They ensure that data is unique, consistent, and meaningful, which supports effective data management and retrieval across various tables and relationships within the database system.

1. Entity Integrity Rule

   • Ensures that each table has a primary key that uniquely identifies each record.
   • Prevents the existence of duplicate records within a table.
   • Requires that primary key values cannot be null, ensuring every record is identifiable.

2. Referential Integrity Rule

   • Maintains consistency between related tables through foreign keys.
   • Ensures that a foreign key value must either match a primary key in another table or be null.
   • Prevents orphaned records by enforcing relationships between tables.

3. Domain Integrity Rule

   • Restricts the type of data that can be stored in a column based on defined data types.
   • Ensures that values fall within a specified range or set of permissible values.
   • Helps maintain valid and meaningful data entries in the database.

4. Key Integrity Rule

   • Ensures that primary keys are unique and not duplicated across records.
   • Guarantees that each record can be uniquely identified, which is crucial for data retrieval.
   • Supports the overall structure and organization of the database.

5. Null Integrity Rule

   • Defines whether a column can accept null values or must contain data.
   • Ensures that critical fields are populated to maintain data completeness.
   • Helps prevent ambiguity in data interpretation by clarifying the presence or absence of values.

6. Unique Constraint Rule

   • Ensures that all values in a specified column are unique across the table.
   • Prevents duplicate entries in columns that require distinct values, aside from the primary key.
   • Enhances data integrity by enforcing uniqueness in non-primary key fields.

7. Check Constraint Rule

   • Allows for the specification of conditions that must be met for data to be entered into a column.
   • Ensures that only valid data that meets certain criteria can be stored.
   • Helps maintain data accuracy and integrity by enforcing business rules at the database level.

8. Semantic Integrity Rule

   • Ensures that the data stored in the database accurately reflects the real-world entities it represents.
   • Enforces business logic and rules that govern the meaning of data.
   • Helps maintain the relevance and correctness of data in relation to its intended use.

9. Business Rule Integrity

   • Enforces specific business rules that dictate how data should be handled within the database.
   • Ensures that the database operations align with organizational policies and procedures.
   • Supports decision-making processes by maintaining data that adheres to business requirements.

10. Cardinality Integrity Rule

    • Defines the relationships between tables in terms of how many instances of one entity relate to another.
    • Ensures that the database accurately represents one-to-one, one-to-many, or many-to-many relationships.
    • Helps maintain the logical structure of the database and supports accurate data retrieval.