【SQL】牛客網SQL訓練Part2 中等難度

阿新 • • 發佈：2022-05-29

查詢當前薪水詳情以及部門編號dept_no

查詢

1、各個部門當前領導的薪水詳情以及其對應部門編號dept_no，

2、輸出結果以salaries.emp_no升序排序，

3、並且請注意輸出結果裡面dept_no列是最後一列

drop table if exists  `salaries` ; 
drop table if exists  `dept_manager` ; 
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
CREATE TABLE `dept_manager` (
`dept_no` char(4) NOT NULL,
`emp_no` int(11) NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
INSERT INTO dept_manager VALUES('d001',10002,'9999-01-01');
INSERT INTO dept_manager VALUES('d002',10006,'9999-01-01');
INSERT INTO dept_manager VALUES('d003',10005,'9999-01-01');
INSERT INTO dept_manager VALUES('d004',10004,'9999-01-01');
INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01');
INSERT INTO salaries VALUES(10002,72527,'2001-08-02','9999-01-01');
INSERT INTO salaries VALUES(10003,43311,'2001-12-01','9999-01-01');
INSERT INTO salaries VALUES(10004,74057,'2001-11-27','9999-01-01');
INSERT INTO salaries VALUES(10005,94692,'2001-09-09','9999-01-01');
INSERT INTO salaries VALUES(10006,43311,'2001-08-02','9999-01-01');
INSERT INTO salaries VALUES(10007,88070,'2002-02-07','9999-01-01');

-- 按員工號聯表查詢
SELECT
	s.*,
	d.`dept_no`
FROM 
	`salaries` AS s
	LEFT JOIN `dept_manager` AS d ON s.`emp_no` = d.`emp_no`
WHERE 
	d.`dept_no` IS NOT NULL -- 必須要有部門才可以
	AND d.TO_DATE = '9999-01-01'  -- 日期必須是當前時間
ORDER BY d.`dept_no` ASC

查詢所有員工的last_name和first_name以及對應部門編號dept_no

包括暫時沒有分配具體部門的員工

drop table if exists  `dept_emp` ; 
drop table if exists  `employees` ; 
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d002','1996-08-03','9999-01-01');
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');

-- 左查詢完成
SELECT
	e.`last_name`,
	e.`first_name`,
	e_no.`dept_no`
FROM 
	`employees` AS e
	LEFT JOIN `dept_emp` AS e_no ON e.`emp_no` = e_no.`emp_no`

獲取所有員工當前的manager

獲取所有的員工和員工對應的經理，如果員工本身是經理的話則不顯示

drop table if exists  `dept_emp` ; 
drop table if exists  `dept_manager` ; 
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `dept_manager` (
`dept_no` char(4) NOT NULL,
`emp_no` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d002','1995-12-03','9999-01-01');
INSERT INTO dept_manager VALUES('d001',10002,'1996-08-03','9999-01-01');
INSERT INTO dept_manager VALUES('d002',10003,'1990-08-05','9999-01-01');

-- 1、先用部門進行關聯，2、再對員工則進行不等關聯，3、取指定時間
SELECT
	emp.emp_no,
	mgr.emp_no AS manager
FROM
	`dept_emp` AS emp
	 JOIN `dept_manager` AS mgr ON emp.dept_no = mgr.dept_no AND emp.emp_no != mgr.emp_no
WHERE 
	mgr.to_date = '9999-01-01'
	AND emp.to_date = '9999-01-01'

統計出當前各個title型別對應的員工當前薪水對應的平均工資

統計出各個title型別對應的員工薪水對應的平均工資avg。

結果給出title以及平均工資avg，並且以avg升序排序

drop table if exists  `salaries` ; 
drop table if exists  titles;
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
CREATE TABLE titles (
`emp_no` int(11) NOT NULL,
`title` varchar(50) NOT NULL,
`from_date` date NOT NULL,
`to_date` date DEFAULT NULL);
INSERT INTO salaries VALUES(10001,88958,'1986-06-26','9999-01-01');
INSERT INTO salaries VALUES(10003,43311,'2001-12-01','9999-01-01');
INSERT INTO salaries VALUES(10004,74057,'1995-12-01','9999-01-01');
INSERT INTO salaries VALUES(10006,43311,'2001-08-02','9999-01-01');
INSERT INTO salaries VALUES(10007,88070,'2002-02-07','9999-01-01');

INSERT INTO titles VALUES(10001,'Senior Engineer','1986-06-26','9999-01-01');
INSERT INTO titles VALUES(10003,'Senior Engineer','2001-12-01','9999-01-01');
INSERT INTO titles VALUES(10004,'Senior Engineer','1995-12-01','9999-01-01');
INSERT INTO titles VALUES(10006,'Senior Engineer','2001-08-02','9999-01-01');
INSERT INTO titles VALUES(10007,'Senior Staff','1996-02-11','9999-01-01');

-- 聯表，然後分組處理，計算AVG薪資
SELECT 
	t.title,AVG(s.salary) AS `avg_salary`
FROM 
	`salaries` AS s
	LEFT JOIN `titles` AS t ON s.emp_no = t.emp_no
GROUP BY t.title 
ORDER BY `avg_salary` ASC

查詢所有員工的last_name和first_name以及對應的dept_name

查詢所有員工的last_name和first_name以及對應的dept_name，也包括暫時沒有分配部門的員工

drop table if exists  `departments` ; 
drop table if exists  `dept_emp` ; 
drop table if exists  `employees` ; 
CREATE TABLE `departments` (
`dept_no` char(4) NOT NULL,
`dept_name` varchar(40) NOT NULL,
PRIMARY KEY (`dept_no`));
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));
INSERT INTO departments VALUES('d001','Marketing');
INSERT INTO departments VALUES('d002','Finance');
INSERT INTO departments VALUES('d003','Human Resources');
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d002','1990-08-05','9999-01-01');
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');

-- 全部左連，因為查詢所有員工，所以員工表是主表
SELECT
	E.last_name,
	E.first_name,
	D.dept_name
FROM
	employees AS E
	LEFT JOIN dept_emp AS DE ON E.emp_no = DE.emp_no
	LEFT JOIN departments AS D ON D.dept_no = DE.dept_no

統計各個部門的工資記錄數

給出部門編碼dept_no、部門名稱dept_name以及部門在salaries表裡面有多少條記錄sum，

按照dept_no升序排序

drop table if exists  `departments` ; 
drop table if exists  `dept_emp` ; 
drop table if exists  `salaries` ; 
CREATE TABLE `departments` (
`dept_no` char(4) NOT NULL,
`dept_name` varchar(40) NOT NULL,
PRIMARY KEY (`dept_no`));
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
INSERT INTO departments VALUES('d001','Marketing');
INSERT INTO departments VALUES('d002','Finance');
INSERT INTO dept_emp VALUES(10001,'d001','2001-06-22','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d002','1996-08-03','9999-01-01');
INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22');
INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01');
INSERT INTO salaries VALUES(10002,72527,'1996-08-03','9999-01-01');
INSERT INTO salaries VALUES(10003,32323,'1996-08-03','9999-01-01');

-- 1、各個部門，即按主表先查詢，然後是中間表和薪資表
-- 2、不能對不查詢的欄位進行分組，所以GroupBy只能對部門號和部門名分組
-- 3、分組後對其他欄位進行COUNT計數即可
SELECT
 D.dept_no,
 D.dept_name,
 COUNT(S.salary) AS sum
FROM
	`departments` AS D
	LEFT JOIN dept_emp AS DE ON D.dept_no = DE.dept_no
	LEFT JOIN salaries AS S ON DE.emp_no = S.emp_no
GROUP BY D.dept_no
ORDER BY D.dept_no ASC

使用join查詢方式找出沒有分類的電影id以及名稱

drop table if exists  film ;
drop table if exists  category  ; 
drop table if exists  film_category  ; 
CREATE TABLE IF NOT EXISTS film (
  film_id smallint(5)  NOT NULL DEFAULT '0',
  title varchar(255) NOT NULL,
  description text,
  PRIMARY KEY (film_id));
CREATE TABLE category  (
   category_id  tinyint(3)  NOT NULL ,
   name  varchar(25) NOT NULL, `last_update` timestamp,
  PRIMARY KEY ( category_id ));
CREATE TABLE film_category  (
   film_id  smallint(5)  NOT NULL,
   category_id  tinyint(3)  NOT NULL, `last_update` timestamp);
INSERT INTO film VALUES(1,'ACADEMY DINOSAUR','A Epic Drama of a Feminist And a Mad Scientist who must Battle a Teacher in The Canadian Rockies');
INSERT INTO film VALUES(2,'ACE GOLDFINGER','A Astounding Epistle of a Database Administrator And a Explorer who must Find a Car in Ancient China');
INSERT INTO film VALUES(3,'ADAPTATION HOLES','A Astounding Reflection of a Lumberjack And a Car who must Sink a Lumberjack in A Baloon Factory');

INSERT INTO category VALUES(1,'Action','2006-02-14 20:46:27');
INSERT INTO category VALUES(2,'Animation','2006-02-14 20:46:27');
INSERT INTO category VALUES(3,'Children','2006-02-14 20:46:27');
INSERT INTO category VALUES(4,'Classics','2006-02-14 20:46:27');
INSERT INTO category VALUES(5,'Comedy','2006-02-14 20:46:27');
INSERT INTO category VALUES(6,'Documentary','2006-02-14 20:46:27');
INSERT INTO category VALUES(7,'Drama','2006-02-14 20:46:27');
INSERT INTO category VALUES(8,'Family','2006-02-14 20:46:27');
INSERT INTO category VALUES(9,'Foreign','2006-02-14 20:46:27');
INSERT INTO category VALUES(10,'Games','2006-02-14 20:46:27');
INSERT INTO category VALUES(11,'Horror','2006-02-14 20:46:27');

INSERT INTO film_category VALUES(1,6,'2006-02-14 21:07:09');
INSERT INTO film_category VALUES(2,11,'2006-02-14 21:07:09');

-- 左連線 + IS NULL 
SELECT
	F.film_id,
	F.title
FROM
	film AS F
	LEFT JOIN film_category AS FC ON F.film_id = FC.film_id
	LEFT JOIN category AS C ON FC.category_id = C.category_id
WHERE FC.film_id IS NULL

使用子查詢的方式找出屬於Action分類的所有電影對應的title,description

drop table if exists   film ;
drop table if exists  category  ; 
drop table if exists  film_category  ; 
CREATE TABLE IF NOT EXISTS film (
  film_id smallint(5)  NOT NULL DEFAULT '0',
  title varchar(255) NOT NULL,
  description text,
  PRIMARY KEY (film_id));
CREATE TABLE category  (
   category_id  tinyint(3)  NOT NULL ,
   name  varchar(25) NOT NULL, `last_update` timestamp,
  PRIMARY KEY ( category_id ));
CREATE TABLE film_category  (
   film_id  smallint(5)  NOT NULL,
   category_id  tinyint(3)  NOT NULL, `last_update` timestamp);
INSERT INTO film VALUES(1,'ACADEMY DINOSAUR','A Epic Drama of a Feminist And a Mad Scientist who must Battle a Teacher in The Canadian Rockies');
INSERT INTO film VALUES(2,'ACE GOLDFINGER','A Astounding Epistle of a Database Administrator And a Explorer who must Find a Car in Ancient China');
INSERT INTO film VALUES(3,'ADAPTATION HOLES','A Astounding Reflection of a Lumberjack And a Car who must Sink a Lumberjack in A Baloon Factory');

INSERT INTO category VALUES(1,'Action','2006-02-14 20:46:27');
INSERT INTO category VALUES(2,'Animation','2006-02-14 20:46:27');
INSERT INTO category VALUES(3,'Children','2006-02-14 20:46:27');
INSERT INTO category VALUES(4,'Classics','2006-02-14 20:46:27');
INSERT INTO category VALUES(5,'Comedy','2006-02-14 20:46:27');
INSERT INTO category VALUES(6,'Documentary','2006-02-14 20:46:27');

INSERT INTO film_category VALUES(1,1,'2006-02-14 21:07:09');
INSERT INTO film_category VALUES(2,1,'2006-02-14 21:07:09');
INSERT INTO film_category VALUES(3,6,'2006-02-14 21:07:09');

-- 子查詢
-- 第一步查詢分類型別為action的記錄，只取主鍵
SELECT category_id FROM category WHERE `name` = 'action'

-- 第二步通過中間表獲取電影的主鍵列表 只取電影主鍵
SELECT film_id FROM film_category WHERE category_id = (
SELECT category_id FROM category WHERE `name` = 'action'
)
-- 第三步 查詢電影表 巢狀上述的子查詢
SELECT `title`, `description`  FROM film WHERE film_id IN (
  SELECT film_id FROM film_category WHERE category_id = (
    SELECT category_id FROM category WHERE `name` = 'action'
  )
)

建立一個actor表

-- 直接把題目的表格貼上過來改改就行了
CREATE TABLE `actor` (
  actor_id smallint(5)	not null comment '主鍵id',
  first_name varchar(45) not null comment '名字',
  last_name varchar(45) not null comment '姓氏',
  last_update date not null comment '日期'
)

批量插入資料，不使用replace操作

對於表actor插入如下資料,如果資料已經存在，請忽略

(不支援使用replace操作)

drop table if exists actor;
CREATE TABLE actor (
   actor_id  smallint(5)  NOT NULL PRIMARY KEY,
   first_name  varchar(45) NOT NULL,
   last_name  varchar(45) NOT NULL,
   last_update  DATETIME NOT NULL);
insert into actor values ('3', 'WD', 'GUINESS', '2006-02-15 12:34:33');


# mysql中常用的三種插入資料的語句:
# insert into表示插入資料，資料庫會檢查主鍵，如果出現重複會報錯；
# replace into表示插入替換資料，需求表中有PrimaryKey，
#             或者unique索引，如果資料庫已經存在資料，則用新資料替換，如果沒有資料效果則和insert into一樣；
# insert ignore表示，如果中已經存在相同的記錄，則忽略當前新資料；
insert ignore into actor values("3","ED","CHASE","2006-02-15 12:34:33");

對first_name建立唯一索引uniq_idx_firstname

針對如下表actor結構建立索引： (注:在 SQLite 中,除了重命名錶和在已有的表中新增列,ALTER TABLE 命令不支援其他操作， mysql支援ALTER TABLE建立索引) 對first_name建立唯一索引uniq_idx_firstname，對last_name建立普通索引idx_lastname

CREATE TABLE actor  (
   actor_id  smallint(5)  NOT NULL PRIMARY KEY,
   first_name  varchar(45) NOT NULL,
   last_name  varchar(45) NOT NULL,
   last_update  datetime NOT NULL);

-- ALTER TABLE 語法新增
ALTER TABLE `now-coder-sql`.`actor` 
ADD UNIQUE INDEX `UNIQ_IDX_FIRST_NAME`(`first_name`) USING BTREE;

ALTER TABLE `now-coder-sql`.`actor` 
ADD INDEX `IDX_LAST_NAME`(`last_name`) USING BTREE;

針對actor表建立檢視actor_name_view

actor表建立檢視actor_name_view，只包含first_name以及last_name兩列，並對這兩列重新命名，

first_name為first_name_v，last_name修改為last_name_v：

後臺會插入2條資料: insert into actor values ('1', 'PENELOPE', 'GUINESS', '2006-02-15 12:34:33'), ('2', 'NICK', 'WAHLBERG', '2006-02-15 12:34:33'); 然後列印檢視名字和插入的資料

drop table if exists actor;
CREATE TABLE  actor  (
   actor_id  smallint(5)  NOT NULL PRIMARY KEY,
   first_name  varchar(45) NOT NULL,
   last_name  varchar(45) NOT NULL,
   last_update datetime NOT NULL);
insert into actor values 
('1', 'PENELOPE', 'GUINESS', '2006-02-15 12:34:33'), 
('2', 'NICK', 'WAHLBERG', '2006-02-15 12:34:33');


-- 對查詢之前編寫一個檢視SQL建立語法
CREATE VIEW `now-coder-sql`.`actor_name_view` AS 

SELECT 
	first_name AS `first_name_v`,
	last_name AS `last_name_v`,
FROM actor;

-- 呼叫檢視
SELECT * FROM actor_name_view

針對salaries表emp_no欄位建立索引idx_emp_no

針對salaries表emp_no欄位建立索引idx_emp_no，查詢emp_no為10005，使用強制索引。後臺會檢查是否使用強制索引

CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
create index idx_emp_no on salaries(emp_no);

-- 強制使用索引語法
SELECT * 
FROM salaries 
FORCE INDEX (idx_emp_no)
WHERE emp_no = 10005

強制使用索引：

https://www.yangdx.com/2020/05/151.html

在last_update後面新增加一列名字為create_date

在last_update後面新增加一列名字為create_date, 型別為datetime, NOT NULL，預設值為'2020-10-01 00:00:00'

drop table if exists actor;
CREATE TABLE  actor  (
   actor_id  smallint(5)  NOT NULL PRIMARY KEY,
   first_name  varchar(45) NOT NULL,
   last_name  varchar(45) NOT NULL,
   last_update  datetime NOT NULL);

-- 指定欄位後面追加
ALTER TABLE actor 
ADD COLUMN `create_date` datetime NOT NULL DEFAULT '2020-10-01 00:00:00' 
AFTER `last_update` ;

構造一個觸發器audit_log

構造一個觸發器audit_log，在向employees_test表中插入一條資料的時候，觸發插入相關的資料到audit中。

後臺會往employees_test插入一條資料: INSERT INTO employees_test (ID,NAME,AGE,ADDRESS,SALARY)VALUES (1, 'Paul', 32, 'California', 20000.00 ); 然後從audit裡面使用查詢語句: select * from audit;

drop table if exists audit;
drop table if exists employees_test;

CREATE TABLE employees_test(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);
CREATE TABLE audit(
    EMP_no INT NOT NULL,
    NAME TEXT NOT NULL
);

-- 建立表格
CREATE TRIGGER `audit_log` 
AFTER INSERT ON `employees_test` FOR EACH ROW 
INSERT INTO audit VALUES(NEW.ID, NEW.`NAME`);

-- 插入測試
INSERT INTO employees_test (ID,NAME,AGE,ADDRESS,SALARY) VALUES 
(1, 'Paul', 32, 'California', 20000.00 );

在audit表上建立外來鍵約束，其emp_no對應employees_test表的主鍵id

後臺會判斷是否建立外來鍵約束，建立輸出1，沒建立輸出0

drop table if exists audit;
drop table if exists employees_test;
CREATE TABLE employees_test(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

CREATE TABLE audit(
    EMP_no INT NOT NULL,
    create_date datetime NOT NULL
);

-- 設定約束外來鍵，指定引用欄位
ALTER TABLE audit
ADD CONSTRAINT FOREIGN KEY (emp_no)
REFERENCES employees_test(id);

將所有獲取獎金的員工當前的薪水增加10%

請你寫出更新語句，將所有獲取獎金的員工當前的(salaries.to_date='9999-01-01')薪水增加10%。 (emp_bonus裡面的emp_no都是當前獲獎的所有員工，不考慮獲取的獎金的型別)。

drop table if exists  emp_bonus; 
drop table if exists  `salaries`;
 
create table emp_bonus(
emp_no int not null,
btype smallint not null
);

CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary`  float(11,1) default NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`)
);

insert into emp_bonus values(10001,1);
INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22');
INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01');

-- 聯表更新
UPDATE `salaries` AS S
JOIN `emp_bonus` AS B ON S.emp_no = B.emp_no
SET S.salary = S.salary * 1.1
WHERE S.to_date = '9999-01-01'

將employees表中的所有員工的last_name和first_name通過引號連線

drop table if exists  `employees` ; 
CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL,
  `birth_date` date NOT NULL,
  `first_name` varchar(14) NOT NULL,
  `last_name` varchar(16) NOT NULL,
  `gender` char(1) NOT NULL,
  `hire_date` date NOT NULL,
  PRIMARY KEY (`emp_no`));
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');
INSERT INTO employees VALUES(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12');
INSERT INTO employees VALUES(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02');
INSERT INTO employees VALUES(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10');
INSERT INTO employees VALUES(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15');
INSERT INTO employees VALUES(10009,'1952-04-19','Sumant','Peac','F','1985-02-18');
INSERT INTO employees VALUES(10010,'1963-06-01','Duangkaew','Piveteau','F','1989-08-24');
INSERT INTO employees VALUES(10011,'1953-11-07','Mary','Sluis','F','1990-01-22');

-- CONCAT 函式實現
SELECT CONCAT(`last_name`, '\'', `first_name`) AS `name` 
FROM employees

查詢字串中逗號出現的次數

drop table if exists strings;
CREATE TABLE strings(
   id int(5)  NOT NULL PRIMARY KEY,
   string  varchar(45) NOT NULL
 );
insert into strings values
(1, '10,A,B'),
(2, 'A,B,C,D'),
(3, 'A,11,B,C,D,E');

-- 1、將引號替換成無字元
-- REPLACE(string, ',', '')

-- 2、源字元長度獲取
-- LENGTH(string)

-- 3、無引號字元長度
-- LENGTH( REPLACE(string, ',', ''))

-- 4、引號的個數 = 源字元長度 - 無引號字元長度
-- LENGTH(string) - LENGTH( REPLACE(string, ',', ''))

-- 5、最終SQL 
-- string長度減去 將逗號替換為空字串的長度 即是 逗號數量 
SELECT
	id,
	LENGTH(string) - LENGTH( REPLACE(string, ',', '')) AS cnt 
FROM strings

獲取employees中的first_name

將employees中的first_name，並按照first_name最後兩個字母升序進行輸出。

drop table if exists  `employees` ; 
CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL,
  `birth_date` date NOT NULL,
  `first_name` varchar(14) NOT NULL,
  `last_name` varchar(16) NOT NULL,
  `gender` char(1) NOT NULL,
  `hire_date` date NOT NULL,
  PRIMARY KEY (`emp_no`));
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');
INSERT INTO employees VALUES(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12');
INSERT INTO employees VALUES(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02');
INSERT INTO employees VALUES(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10');
INSERT INTO employees VALUES(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15');
INSERT INTO employees VALUES(10009,'1952-04-19','Sumant','Peac','F','1985-02-18');
INSERT INTO employees VALUES(10010,'1963-06-01','Duangkaew','Piveteau','F','1989-08-24');
INSERT INTO employees VALUES(10011,'1953-11-07','Mary','Sluis','F','1990-01-22');

-- 排序按 此欄位的最後兩個字元升序
SELECT `first_name` 
FROM `employees` 
ORDER BY RIGHT(`first_name`, 2) ASC

-- 或者直接截取出來排序
SELECT `first_name` 
FROM `employees` 
ORDER BY SUBSTR(`first_name`, -2) ASC

按照dept_no進行彙總

dept_no進行彙總，屬於同一個部門的emp_no按照逗號進行連線，結果給出dept_no以及連接出的結果employees

drop table if exists  `dept_emp` ; 
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d004','1995-12-03','9999-01-01');
INSERT INTO dept_emp VALUES(10004,'d004','1986-12-01','9999-01-01');
INSERT INTO dept_emp VALUES(10005,'d003','1989-09-12','9999-01-01');
INSERT INTO dept_emp VALUES(10006,'d002','1990-08-05','9999-01-01');
INSERT INTO dept_emp VALUES(10007,'d005','1989-02-10','9999-01-01');
INSERT INTO dept_emp VALUES(10008,'d005','1998-03-11','2000-07-31');
INSERT INTO dept_emp VALUES(10009,'d006','1985-02-18','9999-01-01');
INSERT INTO dept_emp VALUES(10010,'d005','1996-11-24','2000-06-26');
INSERT INTO dept_emp VALUES(10010,'d006','2000-06-26','9999-01-01');


-- 分組後再用 GROUP_CONCAT 分組合並處理
SELECT `dept_no`, GROUP_CONCAT(`emp_no`) AS `employees`
FROM `dept_emp`
GROUP BY `dept_no`

平均工資

查詢排除在職(to_date = '9999-01-01' )員工的最大、最小salary之後，其他的在職員工的平均工資avg_salary。

drop table if exists  `salaries` ; 
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` float(11,3) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22');
INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01');
INSERT INTO salaries VALUES(10002,72527,'2001-08-02','9999-01-01');
INSERT INTO salaries VALUES(10003,43699,'2000-12-01','2001-12-01');
INSERT INTO salaries VALUES(10003,43311,'2001-12-01','9999-01-01');
INSERT INTO salaries VALUES(10004,70698,'2000-11-27','2001-11-27');
INSERT INTO salaries VALUES(10004,74057,'2001-11-27','9999-01-01');

-- SQL編寫思路
-- 1、查詢最大的和最小的記錄
-- 2、INNER JOIN 內連線 聯表取反
-- 3、補充WHERE條件
-- 4、對查詢欄位AVG
-- 5、小數位過多，ROUND限制
SELECT
  ROUND( AVG(S.`salary`), 3) AS avg_salary
FROM
  salaries AS S
  JOIN (SELECT * FROM salaries WHERE to_date = '9999-01-01' ORDER BY salary ASC LIMIT 1) AS MIN 
    ON S.emp_no != MIN.emp_no
  JOIN (SELECT * FROM salaries WHERE to_date = '9999-01-01' ORDER BY salary DESC LIMIT 1) AS MAX 
    ON S.emp_no != MAX.emp_no
WHERE S.to_date = '9999-01-01'

分頁查詢employees表，每5行一頁，返回第2頁的資料

drop table if exists  `employees` ; 
CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL,
  `birth_date` date NOT NULL,
  `first_name` varchar(14) NOT NULL,
  `last_name` varchar(16) NOT NULL,
  `gender` char(1) NOT NULL,
  `hire_date` date NOT NULL,
  PRIMARY KEY (`emp_no`));
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');
INSERT INTO employees VALUES(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12');
INSERT INTO employees VALUES(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02');
INSERT INTO employees VALUES(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10');
INSERT INTO employees VALUES(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15');
INSERT INTO employees VALUES(10009,'1952-04-19','Sumant','Peac','F','1985-02-18');
INSERT INTO employees VALUES(10010,'1963-06-01','Duangkaew','Piveteau','F','1989-08-24');
INSERT INTO employees VALUES(10011,'1953-11-07','Mary','Sluis','F','1990-01-22');


-- LIMIT X OFFSET Y  
-- X size 展示多少
-- Y offset 從哪條記錄開始

-- 如果不寫 OFFSET , 就反過來， X是偏移，Y是展示數
SELECT *
FROM `employees`
LIMIT 5 OFFSET 5

使用含有關鍵字exists查詢未分配具體部門的員工的所有資訊

drop table if exists employees;
drop table if exists dept_emp;
CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL,
  `birth_date` date NOT NULL,
  `first_name` varchar(14) NOT NULL,
  `last_name` varchar(16) NOT NULL,
  `gender` char(1) NOT NULL,
  `hire_date` date NOT NULL,
  PRIMARY KEY (`emp_no`));
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26');
INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21');
INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28');
INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01');
INSERT INTO employees VALUES(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12');
INSERT INTO employees VALUES(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02');
INSERT INTO employees VALUES(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10');
INSERT INTO employees VALUES(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15');
INSERT INTO employees VALUES(10009,'1952-04-19','Sumant','Peac','F','1985-02-18');
INSERT INTO employees VALUES(10010,'1963-06-01','Duangkaew','Piveteau','F','1989-08-24');
INSERT INTO employees VALUES(10011,'1953-11-07','Mary','Sluis','F','1990-01-22');
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d004','1995-12-03','9999-01-01');
INSERT INTO dept_emp VALUES(10004,'d004','1986-12-01','9999-01-01');
INSERT INTO dept_emp VALUES(10005,'d003','1989-09-12','9999-01-01');
INSERT INTO dept_emp VALUES(10006,'d002','1990-08-05','9999-01-01');
INSERT INTO dept_emp VALUES(10007,'d005','1989-02-10','9999-01-01');
INSERT INTO dept_emp VALUES(10008,'d005','1998-03-11','2000-07-31');
INSERT INTO dept_emp VALUES(10009,'d006','1985-02-18','9999-01-01');
INSERT INTO dept_emp VALUES(10010,'d005','1996-11-24','2000-06-26');
INSERT INTO dept_emp VALUES(10010,'d006','2000-06-26','9999-01-01');


-- 查詢存在 D表中關聯E表的記錄
-- 如果存在 關聯不到的記錄，觸發NOT EXISTS 條件 
SELECT * 
FROM employees e 
WHERE NOT EXISTS ( 
	SELECT emp_no 
	FROM dept_emp d 
	WHERE d.emp_no = e.emp_no 
);

刷題通過的題目排名

輸出通過的題目的排名，通過題目個數相同的，排名相同，此時按照id升序排列

drop table if exists passing_number;
CREATE TABLE `passing_number` (
`id` int(4) NOT NULL,
`number` int(4) NOT NULL,
PRIMARY KEY (`id`));

INSERT INTO passing_number VALUES
(1,4),
(2,3),
(3,3),
(4,2),
(6,4),
(5,5);

-- 8版本開窗函式解決
SELECT
	id,
	number,
	dense_rank() over ( ORDER BY number DESC ) AS t_rank 
FROM
	passing_number;
	
-- 5版本解決辦法，找大於等於自己的SQL
SELECT
	p1.id,
	p1.number,
	( SELECT count( DISTINCT p2.number ) 
	FROM passing_number AS p2 
	WHERE p2.number >= p1.number ) AS t_rank 
FROM
	passing_number AS p1 
ORDER BY
	number DESC,
	id ASC

考試分數(二)

查詢使用者分數大於其所在工作(job)分數的平均分的所有grade的屬性，並且以id的升序排序

drop table if exists grade;
CREATE TABLE  grade(
`id` int(4) NOT NULL,
`job` varchar(32) NOT NULL,
`score` int(10) NOT NULL,
PRIMARY KEY (`id`));

INSERT INTO grade VALUES
(1,'C++',11001),
(2,'C++',10000),
(3,'C++',9000),
(4,'Java',12000),
(5,'Java',13000),
(6,'JS',12000),
(7,'JS',11000),
(8,'JS',9999),
(9,'Java',12500);

-- 先做平均分表，然後聯表計算
SELECT MAIN.*
FROM `grade` AS MAIN
JOIN (
  SELECT `job`, AVG(`score`) AS `AVG_SCORE`
  FROM `grade`
  GROUP BY `job`
) AS AVG_TAB ON MAIN.`job` = AVG_TAB.`job`
WHERE MAIN.`score` > AVG_TAB.`AVG_SCORE`
ORDER BY MAIN.`id` ASC

課程訂單分析(二)

查詢在2025-10-15以後，

同一個使用者下單2個以及2個以上狀態為購買成功的C++課程或Java課程或Python課程的user_id，並且按照user_id升序排序

drop table if exists order_info;
CREATE TABLE order_info (
id int(4) NOT NULL,
user_id int(11) NOT NULL,
product_name varchar(256) NOT NULL,
status varchar(32) NOT NULL,
client_id int(4) NOT NULL,
date date NOT NULL,
PRIMARY KEY (id));

INSERT INTO order_info VALUES
(1,557336,'C++','no_completed',1,'2025-10-10'),
(2,230173543,'Python','completed',2,'2025-10-12'),
(3,57,'JS','completed',3,'2025-10-23'),
(4,57,'C++','completed',3,'2025-10-23'),
(5,557336,'Java','completed',1,'2025-10-23'),
(6,57,'Java','completed',1,'2025-10-24'),
(7,557336,'C++','completed',1,'2025-10-25');

-- 主要是日期的查詢
SELECT `user_id`
FROM `order_info`
WHERE 1 = 1
　 AND `date` >= '2025-10-15'
  AND `status` = 'completed'
  AND `product_name` IN ('C++', 'Java', 'Python')
GROUP BY `user_id`
HAVING COUNT(`user_id`) > 1

課程訂單分析(三)

查詢在2025-10-15以後，

同一個使用者下單2個以及2個以上狀態為購買成功的C++課程或Java課程或Python課程的訂單資訊，並且按照order_info的id升序排序

drop table if exists order_info;
CREATE TABLE order_info (
id int(4) NOT NULL,
user_id int(11) NOT NULL,
product_name varchar(256) NOT NULL,
status varchar(32) NOT NULL,
client_id int(4) NOT NULL,
date date NOT NULL,
PRIMARY KEY (id));

INSERT INTO order_info VALUES
(1,557336,'C++','no_completed',1,'2025-10-10'),
(2,230173543,'Python','completed',2,'2025-10-12'),
(3,57,'JS','completed',3,'2025-10-23'),
(4,57,'C++','completed',3,'2025-10-23'),
(5,557336,'Java','completed',1,'2025-10-23'),
(6,57,'Java','completed',1,'2025-10-24'),
(7,557336,'C++','completed',1,'2025-10-25');


-- 先篩選買了兩套以上的，再看其他條件
SELECT *
FROM `order_info` WHERE 
	`user_id` IN (
		SELECT `user_id`
		FROM `order_info`
		GROUP BY `user_id`
		HAVING COUNT(`user_id`) > 1
	)
	AND `date` >= '2025-10-15'
	AND `status` = 'completed'
	AND `product_name` IN ('C++', 'Java', 'Python')
ORDER BY `id` ASC

課程訂單分析(六)

查詢在2025-10-15以後，

同一個使用者下單2個以及2個以上狀態為購買成功的C++課程或Java課程或Python課程的訂單id，

是否拼團以及客戶端名字資訊，最後一列如果是非拼團訂單，則顯示對應客戶端名字，如果是拼團訂單，則顯示NULL，並且按照order_info的id升序排序

drop table if exists order_info;
drop table if exists client;
CREATE TABLE order_info (
id int(4) NOT NULL,
user_id int(11) NOT NULL,
product_name varchar(256) NOT NULL,
status varchar(32) NOT NULL,
client_id int(4) NOT NULL,
date date NOT NULL,
is_group_buy varchar(32) NOT NULL,
PRIMARY KEY (id));

CREATE TABLE client(
id int(4) NOT NULL,
name varchar(32) NOT NULL,
PRIMARY KEY (id)
);

INSERT INTO order_info VALUES
(1,557336,'C++','no_completed',1,'2025-10-10','No'),
(2,230173543,'Python','completed',2,'2025-10-12','No'),
(3,57,'JS','completed',0,'2025-10-23','Yes'),
(4,57,'C++','completed',3,'2025-10-23','No'),
(5,557336,'Java','completed',0,'2025-10-23','Yes'),
(6,57,'Java','completed',1,'2025-10-24','No'),
(7,557336,'C++','completed',0,'2025-10-25','Yes');

INSERT INTO client VALUES
(1,'PC'),
(2,'Android'),
(3,'IOS'),
(4,'H5')


-- 1、用上一題的作為主表左連線客戶端表，存在沒有客戶端的情況
-- 2、然後對NULL的客戶端名稱進行 空處理
SELECT
	MAIN.id,
	MAIN.is_group_buy,
	IFNULL(client.`name`, 'None') AS `client_name`
FROM 
 (SELECT *
FROM `order_info` WHERE 
	`user_id` IN (
		SELECT `user_id`
		FROM `order_info`
		GROUP BY `user_id`
		HAVING COUNT(`user_id`) > 1
	)
	AND `date` >= '2025-10-15'
	AND `status` = 'completed'
	AND `product_name` IN ('C++', 'Java', 'Python')
ORDER BY `id` ASC) AS MAIN
LEFT JOIN client ON client.id =  MAIN.client_id

實習廣場投遞簡歷分析(二)

查詢在2025年內投遞簡歷的每個崗位，

每一個月內收到簡歷的數量，並且按先按月份降序排序，再按簡歷數目降序排序

drop table if exists resume_info;
CREATE TABLE resume_info (
id int(4) NOT NULL,
job varchar(64) NOT NULL,
date date NOT NULL,
num int(11) NOT NULL,
PRIMARY KEY (id));

INSERT INTO resume_info VALUES
(1,'C++','2025-01-02',53),
(2,'Python','2025-01-02',23),
(3,'Java','2025-01-02',12),
(4,'C++','2025-01-03',54),
(5,'Python','2025-01-03',43),
(6,'Java','2025-01-03',41),
(7,'Java','2025-02-03',24),
(8,'C++','2025-02-03',23),
(9,'Python','2025-02-03',34),
(10,'Java','2025-02-04',42),
(11,'C++','2025-02-04',45),
(12,'Python','2025-02-04',59),
(13,'Python','2025-03-04',54),
(14,'C++','2025-03-04',65),
(15,'Java','2025-03-04',92),
(16,'Python','2025-03-05',34),
(17,'C++','2025-03-05',34),
(18,'Java','2025-03-05',34),
(19,'Python','2026-01-04',230),
(20,'C++','2026-02-06',231);

-- 主要是對記錄進行兩個欄位的分組，和月份的處理
SELECT
	job,
	date_format( date, '%Y-%m' ) AS mon,
	sum( num ) AS cnt 
FROM
	resume_info 
WHERE
	YEAR(date) = 2025 
GROUP BY job, mon 
ORDER BY mon DESC, cnt DESC;

最差是第幾名(一)

如果一個學生知道了自己綜合成績以後，最差是排第幾名? 結果按照grade升序排序

drop table if exists class_grade;
CREATE TABLE class_grade (
grade varchar(32) NOT NULL,
number int(4) NOT NULL
);

INSERT INTO class_grade VALUES
('A',2),
('D',1),
('C',2),
('B',2);

-- 查詢
SELECT
	c1.grade,
	SUM( c2.number ) AS t_rank 
FROM
	class_grade c1
	CROSS JOIN class_grade c2 ON c1.grade >= c2.grade 
GROUP BY
	c1.grade 
ORDER BY
	c1.grade ASC;

獲得積分最多的人(一)

查詢積分增加最高的使用者的名字，以及他的總積分是多少(此題資料保證積分最高的使用者有且只有1個)

drop table if exists user;
drop table if exists grade_info;

CREATE TABLE user (
id  int(4) NOT NULL,
name varchar(32) NOT NULL
);

CREATE TABLE grade_info (
user_id  int(4) NOT NULL,
grade_num int(4) NOT NULL,
type varchar(32) NOT NULL
);

INSERT INTO user VALUES
(1,'tm'),
(2,'wwy'),
(3,'zk'),
(4,'qq'),
(5,'lm');

INSERT INTO grade_info VALUES
(1,3,'add'),
(2,3,'add'),
(1,1,'add'),
(3,3,'add'),
(4,3,'add'),
(5,3,'add');

-- 查詢最大的那一個，然後聯表獲取
  SELECT `USER`.`NAME`,
	t.grade_sum 
FROM
	( 
		SELECT user_id, sum( grade_num ) AS grade_sum 
		FROM grade_info 
		GROUP BY user_id 
		ORDER BY grade_sum DESC 
		LIMIT 1 
	) t
	JOIN `USER` ON t.user_id = USER.id

商品交易(網易校招筆試真題)

查詢購買個數超過20,質量小於50的商品，按照商品id升序排序

CREATE TABLE `goods` (
  `id` int(11) NOT NULL,
  `name` varchar(10)  DEFAULT NULL,
  `weight` int(11) NOT NULL,
  PRIMARY KEY (`id`)
);
CREATE TABLE `trans` (
  `id` int(11) NOT NULL,
  `goods_id` int(11) NOT NULL,
  `count` int(11) NOT NULL,
  PRIMARY KEY (`id`)
);
insert into goods values(1,'A1',100);
insert into goods values(2,'A2',20);
insert into goods values(3,'B3',29);
insert into goods values(4,'T1',60);
insert into goods values(5,'G2',33);
insert into goods values(6,'C0',55);
insert into trans values(1,3,10);
insert into trans values(2,1,44);
insert into trans values(3,6,9);
insert into trans values(4,1,2);
insert into trans values(5,2,65);
insert into trans values(6,5,23);
insert into trans values(7,3,20);
insert into trans values(8,2,16);
insert into trans values(9,4,5);
insert into trans values(10,1,3);

-- 聯表之後再進行分組查詢
SELECT
	g.id,
	g.NAME,
	g.weight,
	sum( t.count ) ss 
FROM
	trans t
	LEFT JOIN goods g ON t.goods_id = g.id 
GROUP BY
	t.goods_id 
HAVING
	( ss > 20 AND g.weight < 50 ) 
ORDER BY
	g.id ASC

【SQL】 牛客網SQL訓練Part2 中等難度

查詢當前薪水詳情以及部門編號dept_no

查詢所有員工的last_name和first_name以及對應部門編號dept_no

獲取所有員工當前的manager

統計出當前各個title型別對應的員工當前薪水對應的平均工資

查詢所有員工的last_name和first_name以及對應的dept_name

統計各個部門的工資記錄數

使用join查詢方式找出沒有分類的電影id以及名稱

使用子查詢的方式找出屬於Action分類的所有電影對應的title,description

建立一個actor表

批量插入資料，不使用replace操作

對first_name建立唯一索引uniq_idx_firstname

針對actor表建立檢視actor_name_view

針對salaries表emp_no欄位建立索引idx_emp_no

在last_update後面新增加一列名字為create_date

構造一個觸發器audit_log

在audit表上建立外來鍵約束，其emp_no對應employees_test表的主鍵id

將所有獲取獎金的員工當前的薪水增加10%

將employees表中的所有員工的last_name和first_name通過引號連線

查詢字串中逗號出現的次數

獲取employees中的first_name

按照dept_no進行彙總

平均工資

分頁查詢employees表，每5行一頁，返回第2頁的資料

使用含有關鍵字exists查詢未分配具體部門的員工的所有資訊

刷題通過的題目排名

考試分數(二)

課程訂單分析(二)

課程訂單分析(三)

課程訂單分析(六)

實習廣場投遞簡歷分析(二)

最差是第幾名(一)

獲得積分最多的人(一)

商品交易(網易校招筆試真題)

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【SQL】牛客網SQL訓練Part2 中等難度