Basic Queries

Master the fundamentals of querying data in Databend. Start here if you're new to SQL or need a refresher on core concepts.

What You'll Learn

• Select and filter data effectively
• Sort and limit query results
• Group data and calculate aggregates
• Use advanced grouping techniques

Query Essentials

Filtering & Selection

Learn the basics: SELECT, WHERE, ORDER BY, and LIMIT

SELECT name, salary FROM employees 
WHERE department = 'Engineering' 
ORDER BY salary DESC;

Aggregating Data

Summarize data with GROUP BY and aggregate functions

SELECT department, AVG(salary) as avg_salary
FROM employees 
GROUP BY department;

Advanced Grouping

Multi-dimensional analysis with CUBE, ROLLUP, and GROUPING SETS

-- Generate all possible grouping combinations
SELECT department, job_level, COUNT(*)
FROM employees 
GROUP BY CUBE(department, job_level);

Quick Reference

Most Common Patterns

-- Top N query
SELECT * FROM table ORDER BY column DESC LIMIT 10;

-- Count by category  
SELECT category, COUNT(*) FROM table GROUP BY category;

-- Filter and aggregate
SELECT region, AVG(sales) 
FROM orders 
WHERE order_date >= '2023-01-01'
GROUP BY region
HAVING AVG(sales) > 1000;

Next Steps

Once you're comfortable with basic queries:

• Combining Data - JOIN tables and use CTEs
• Advanced Features - Custom functions and procedures