#案例：查詢員工的工資級別

SELECT
  salary,grade_level
FROM
  employees e
JOIN
  job_grades g
ON
  e.`salary` BETWEEN g.`lowest_sal` AND g.`lowest_sal`;

#案例：查詢每個工資級別的個數，並且按級別降序

SELECT
  COUNT(*),grade_level
FROM
  job_grades j
JOIN
  employees e
ON
  e.`salary` BETWEEN j.`lowest_sal`AND j.`highest_sal`
GROUP BY
  grade_level DESC;

內容擴充套件：

語法

select 查詢列表

from 表1 別名 [連線型別]

jion 表2 別名

on 連線條件

[where 篩選條件]

[group by 分組]

[having 篩選條件]

[order by 排序列表]

案例1:查詢員工名,部門名

SELECT last_name,department_name
FROM employees e
INNER JOIN departments d
ON e.department_id=d.department_id;

案例2:查詢名字中包含e的員工名和工種名(新增篩選)

SELECT last_name,job_title
FROM employees e
INNER JOIN jobs j
ON e.job_id=j.job_id
WHERE e.last_name LIKE ‘%e%';

以上就是本次介紹的全部知識點內容。