SQL查询-除了旋转之外，还有更多的选项和建议

SELECT 
    department,
    SUM(CASE WHEN status = 'completed' THEN 1 ELSE 0 END) AS completed_tasks,
    SUM(CASE WHEN status = 'pending' THEN 1 ELSE 0 END) AS pending_tasks
FROM 
    tasks
GROUP BY 
    department;

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2;

SELECT t1.column1, t2.column2
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.table1_id;

SELECT column1, column2
FROM table1
WHERE id IN (SELECT id FROM table2 WHERE status = 'active');

SELECT 
    column1,
    column2,
    RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS rank
FROM 
    employees;

SELECT department, AVG(salary) AS average_salary
FROM employees
GROUP BY department;

SELECT department, AVG(salary) AS average_salary
FROM employees
GROUP BY department
HAVING AVG(salary) > 50000;

SELECT * FROM employees
ORDER BY id
LIMIT 10 OFFSET 20;

SELECT * FROM employees e
WHERE EXISTS (SELECT 1 FROM departments d WHERE d.id = e.department_id AND d.name = 'Sales');

WITH active_employees AS (
    SELECT * FROM employees WHERE status = 'active'
)
SELECT * FROM active_employees
WHERE department = 'Engineering';