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Comet

#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.

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