Important SQL Topics For Interview
 |
| Sql Topics For Interview |
1. Basic SQL queries:
Understand the fundamentals of SQL syntax, including SELECT, FROM, WHERE, GROUP BY, HAVING, and ORDER BY clauses. Be able to write simple queries to retrieve data from a single table.
2. Joins:
Learn about different types of joins, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN. Understand how to join multiple tables based on related columns.
3. Subqueries:
Familiarize yourself with subqueries, which are queries nested within another query. Know how to use subqueries in the SELECT, FROM, WHERE, and HAVING clauses.
4. Aggregation functions:
Gain knowledge of aggregate functions like COUNT, SUM, AVG, MIN, and MAX. Understand how to use these functions in combination with GROUP BY to generate summary statistics.
5. Data manipulation:
Be proficient in INSERT, UPDATE, and DELETE statements to manipulate data within a database. Understand how to modify existing records or add new records to a table.
6. Indexes:
Learn about indexes and their role in enhancing query performance. Understand how to create indexes on appropriate columns and how they impact query execution.
7. Constraints:
Understand the purpose and usage of constraints such as PRIMARY KEY, FOREIGN KEY, UNIQUE, and NOT NULL. Be able to define and enforce these constraints on tables.
8. Views:
Familiarize yourself with views, which are virtual tables derived from the result of a query. Understand how to create views and use them to simplify complex queries or provide a layer of abstraction.
9. Normalization:
Gain an understanding of database normalization concepts (e.g., first normal form, second normal form, third normal form) and the benefits of designing a well-normalized database schema.
10. Transactions and ACID properties:
Learn about transactions and their importance in maintaining data integrity. Understand the ACID properties (Atomicity, Consistency, Isolation, Durability) and how they ensure reliable data operations.
Remember to practice writing SQL queries and working with sample databases to solidify your understanding of these topics before the interview.
