Data Integrity

Data Integrity means ensuring that the data in a database is accurate, consistent, and reliable over its entire lifecycle. It prevents errors, duplicates, and corruption.

Types of Data Integrity:

1. Entity Integrity

   • Ensures each row in a table is unique, often using a primary key.

2. Referential Integrity

   • Ensures relationships between tables stay consistent, using foreign keys to link tables properly.

3. Domain Integrity

   • Ensures that data entered is valid and follows defined rules, such as data type, format, or range (e.g., age must be a positive number).

4. User-Defined Integrity

   • Custom rules set by the user or application, such as business logic (e.g., an order date cannot be in the future).

🔍 Indexing

Indexing is a technique to speed up searching and querying data in a database.

• An index works like the index in a book: it helps the database quickly locate rows without scanning the entire table.

• Indexes are created on columns that are often used in search conditions (e.g., WHERE clauses).

Benefits of Indexing:

• Much faster data retrieval

• Improved performance for SELECT queries

Downsides:

• Indexes take extra storage space.

• Slows down INSERT, UPDATE, and DELETE operations slightly because indexes must be updated too.