Oracle Database uses a number of features to ensure data integrity, including:
1. Primary Keys: A primary key is a unique identifier for a row in a table. It ensures that each row is uniquely identified and helps to prevent duplicate data.
2. Foreign Keys: A foreign key is a column or group of columns in a table that references a primary key in another table. This helps to ensure that related data is consistent across multiple tables.
3. Constraints: Constraints are used to enforce certain data integrity rules. For example, a NOT NULL constraint prevents null values from being inserted into a column.
4. Triggers: Triggers are code that is executed when certain database events occur. They can be used to check data integrity and enforce business rules.
5. Indexes: Indexes can be used to quickly search for data and ensure that data is stored in a consistent format.
6. Encryption: Data can be encrypted to ensure that it is secure and can only be accessed by authorized users.