56. What is normalization?
Organizing data to reduce redundancy.
57. What are indexes?
Database structures that improve query speed.
58. Clustered vs Non-clustered index?
Clustered defines physical data order.
Non-clustered is separate structure pointing to data.
59. What is a stored procedure?
Precompiled SQL code stored in database.
60. What is a transaction?
Group of operations executed as a single unit.
61. What is ACID?
Atomicity
Consistency
Isolation
Durability
62. SQL vs NoSQL?
SQL = relational, structured.
NoSQL = flexible schema, scalable.
63. When use NoSQL?
High scalability, unstructured data, real-time apps.
64. What is a foreign key?
A column that links two tables.
65. How do you optimize slow queries?
- Indexing
- Avoid SELECT *
- Query plan analysis
- Proper joins