mysql grouped screening

After packet screening conditions, the result of screening is to do a screening, it is placed at the end, if the result of screening and a screening of independent, then in the middle

Case # 1: Query number of employees of the department> 2

SELECT 
    COUNT(*),department_id
FROM
    employees
GROUP BY
    department_id
HAVING
    COUNT(*)>2;

#: Maximum wage jobs have to query each employee bonuses> jobs numbered 12,000 and the highest salary

SELECT
    MAX(salary),job_id
FROM
    employees
WHERE
    commission_pct IS NOT NULL 
GROUP BY
    job_id
HAVING
    MAX(salary)>12000; #筛选12000放在分组后是因为，要等Max计算完再开始筛选

# Inquiry leading number> leading men of each employee's minimum wage> 102 leading number 5000, and its lowest wages

SELECT
    MIN(salary),manager_id
FROM
    employees
WHERE
    manager_id>102
GROUP BY
    manager_id
HAVING MIN(salary)>5000;