中級工程師基礎SQL試題

一、查詢員工的全名，email和電話

SELECT
concat(first_name,',',last_name),email,phone_int
 //將employees表的所有員工的last_name和first_name拼接起來作為Name
FROM employees;

二、查詢所有員工的全名，月薪和年薪（月薪*12）

SELECT
first_name,last_name,salary,salary*12 
FROM employees;

三、查詢所有員工的全名，月薪和年終獎(年薪*commission_pct)

SELECT
first_name,last_name,salary,salary*12*ifnull(commission_pct,0)
//IFNULL函式是MySQL控制流函式之一，它接受兩個引數，如果不是NULL，則回傳第一個引數，否則，IFNULL函式回傳第二個引數，
//傭金百分比 (CommissionPCT)但是傭金百分比，資料庫里employees表里的一個列，
 FROM employees;

四、查詢哪些部門和職位有員工

SELECT DISTINCT department_id,job_id from employees WHERE department_id is not null
//SELECT DISTINCT用于回傳唯一不同的值

五、查詢1999年之后入職的員工資訊

SELECT first_name,last_name,hire_date FROM employees WHERE year(hire_date) >= '1999'

六、查詢公司的老板資訊

SELECT first_name,last_name FROM employees WHERE manager_id IS NULL

七、查詢所有員工資訊，按照部門和年薪降序排序；

SELECT first_name,last_name,salary*12 as total FROM employees ORDER BY department_id,total DESC
//ORDER BY 關鍵字用于對結果集按照一個列或者多個列進行排列，
//ORDER BY 關鍵字默認按照升序進行排序，DESC降序

八、給用戶名加密，保留員工全名前3位，中間4位使用*代替，如果姓名還有多余的字符，保留；

SELECT concat(RPAD(substring(concat(first_name,last_name),1,3),7,'*'),
SUBSTRING(concat(first_name,last_name),8)) 
FROM employees

九、計算員工姓名和全薪；

SELECT first_name,last_name,salary,salary*12*(1+ifnull(commission_pct,0)) FROM employees

十、查詢員工所屬的部門id，如果沒有部門，列印“未分配部門”

SELECT first_name,last_name,ifnull(department_id,'未分配部門') FROM employees

十一、查詢出每一個部門的平均工資

SELECT department_id,AVG(salary) FROM employees WHERE department_id is not null GROUP BY department_id 

十二、查詢平均工資高于8000的部門和其平均工資

SELECT department_id,AVG(salary) FROM employees WHERE department_id is not null GROUP BY department_id HAVING AVG(salary)>=8000

十三、查詢換過作業員工換作業的次數

SELECT employee_id,COUNT(employee_id) FROM job_history GROUP BY employee_id

十四、查詢在95，96，97，98年各進公司多少人

SELECT year(hire_date),count(employee_id)
FROM employees
WHERE YEAR(hire_date) in ('1995','1996','1997','1998')
GROUP BY YEAR(hire_date)

十五、輸出員工名稱，員工id，員工所屬部門

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

十六、輸出員工資訊，包括employee_id, first_name,

    department_id,  department_name   location_id     city
SELECT e.employee_id,e.first_name,d.department_id,d.department_name,l.location_id,l.city
FROM employees e JOIN departments d ON e.department_id = d.department_id JOIN locations l ON d.location_id = l.location_id

十七、在 EMPLOYEES 表中所有薪水位于JOB_GRADES表最低薪水和最高薪水之間雇員的薪水級別

SELECT e.first_name,e.last_name,e.salary
FROM employees e,job_grades j
WHERE e.salary BETWEEN j.lowest_sal AND j.highest_sal
SELECT e.first_name,e.last_name,e.salary
FROM employees e JOIN job_grades j ON e.salary BETWEEN j.lowest_sal AND j.highest_sal

十八、查詢所有有獎金的員工的姓名，部門，地址，城市

SELECT e.employee_id,e.first_name,d.department_id,d.department_name,l.location_id,l.city
FROM employees e JOIN departments d ON e.department_id = d.department_id JOIN locations l ON d.location_id = l.location_id
WHERE e.commission_pct IS NOT NULL

十九、查詢last_name為’Ki’ 的員工的經理資訊

SELECT first_name,last_name FROM employees WHERE employee_id IN (SELECT manager_id FROM employees WHERE last_name LIKE 'Ki%')
//IN運算子允許where子句中規定多個值
//LIKE運算子用于WHERE子句中搜索列中的指定模式

二十、查詢公司工資最低的員工資訊

SELECT first_name,last_name,salary FROM employees WHERE salary = (SELECT MIN(salary) FROM employees)

二十一、查詢1999年來公司的所有員工的最高工資的員工

SELECT first_name,last_name,hire_date,salary
FROM employees WHERE salary=
(SELECT MAX(salary) FROM employees WHERE year(hire_date)='1999')
AND year(hire_date) = '1999'
//WHERE子句用于過濾記錄

.二十二、查詢曾經做過ST_CLERK的員工資訊

SELECT e.first_name,e.last_name,j.job_id FROM employees e JOIN job_history j ON e.employee_id = j.employee_id WHERE j.job_id = 'ST_CLERK'