#freelancer • 1y
Here are some essential SQL topics for data analysts: 1. Basic Queries: SELECT, FROM, WHERE clauses. 2. Sorting and Filtering: ORDER BY, GROUP BY, HAVING. 3. Joins: INNER JOIN, LEFT JOIN, RIGHT JOIN. 4. Aggregation Functions: COUNT, SUM, AVG, MIN, MAX. 5. Subqueries: Embedding queries within queries. 6. Data Modification: INSERT, UPDATE, DELETE. 7. Indexes: Optimizing query performance. 8. Normalization: Efficient database design. 9. Views: Creating virtual tables for simplified queries. 10. Database Relationships: One-to-One, One-to-Many, Many-to-Many. Window functions are also important: - ROW_NUMBER(): Assigns a unique number to each row. - RANK() and DENSE_RANK(): Rank data with ties handling. - LAG() and LEAD(): Access data from preceding or following rows. - SUM(), AVG(), MIN(), MAX(): Aggregations over a defined window.
Every Dream is Worth... • 5m
Founder: The app is slow. Can we just increase the server size? Backend Dev: So you want to pay more instead of fixing the problem? Founder: ...What's the problem? Backend Dev: Too many database queries, no caching, and inefficient API calls. Fo
See MoreFull Stack Web Devel... • 8m
Security testing ensures that applications are free from vulnerabilities like SQL Injection, XSS, CSRF, and IDOR. SQL Injection occurs when unsanitized inputs allow attackers to manipulate database queries. This can be mitigated by using parameterize
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