题解 | 获取有奖金的员工相关信息。

-- 用连接去做，核心是有奖金的用户，那么emp_bonus应该为基表
SELECT 
    t1.emp_no,
    t2.first_name,
    t2.last_name,
    t1.btype,
    t3.salary,
    ROUND(CASE 
        WHEN t1.btype = 1 THEN t3.salary * 0.1
        WHEN t1.btype = 2 THEN t3.salary * 0.2
        ELSE t3.salary*0.3
        END,1) bonus
FROM emp_bonus t1
LEFT JOIN employees t2
ON t1.emp_no = t2.emp_no
LEFT JOIN salaries t3
ON t1.emp_no = t3.emp_no
WHERE t3.to_date = '9999-01-01'
ORDER BY emp_no