如何構建此SQL SELECT查詢？

Question

我有兩個表，我需要做一定的選擇。

第一個表是僱工有colums 名稱 * Departament_ID *和工資 第二個表是Departament有colums Departament ID和* Departament_Name *

我的SQL腳本有拿到我的姓名,最高賽樂和最低工資其中Departament_ID是'30'

Answer 1

這樣的事情應該可以做到這一點（注意：所有的拼寫都與你在第一篇文章中給出的完全相同）。

SELECT d.Department_Name AS name, 
      MAX(e.salary) AS max_salary, 
      MIN(e.salary) AS min_salary 
    FROM Department d 
LEFT JOIN Employe e ON d.Department_ID = e.Department_ID 
    WHERE d.Department_ID = 30 

Answer 2

SELECT d.department_name, 
     MIN(e.salary) AS 'Minimum Salary', 
     MAX(e.salary) AS 'Maximum Salary' 
FROM department d,employee e 
WHERE d.department_id=30 AND d.department_id=e.department_id 
GROUP BY d.department_name 

Answer 3

SELECT max(sal) as MaximumSalary 
     ,min(sal) as MinimumSalary 
     ,department.Departament_Name 
     ,employee.Name 
FROM employee 
INNER JOIN department ON 
      employee.departmentid = department.department_id 
WHERE department.department_id = 31 
GROUP BY department.department_id 

最大值和最小值功能會給你的薪水列的最大和僱員表的最小值。這將要求您使用GROUP BY，因爲他們需要計算一組數據中的最大值和最小值，在這種情況下，按部門計算最大值/最小值。我們按部門ID分組，因爲它是表格的唯一鍵。內部聯結在這裏加入你擁有的兩個表。這是一個內部聯接，因爲我們想讓部門進入查詢。

Answer 4

SELECT d.Department_Name AS name, 
     MAX(e.salary) AS max_salary, 
     MIN(e.salary) AS min_salary 
    FROM Department d 
    Inner JOIN Employee ON d.Department_ID = e.Department_ID 
    WHERE d.Department_ID = 30