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线上＋线下≠新零售，6大互通诠释新零售的核心要点-亿发

金刚豆 2024-12-02 阅读 5
数据库sql面试
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数据表关系图

在这里插入图片描述

数据表

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `sex` enum('female','male') NOT NULL,
  `birth` date NOT NULL,
  `credit` float(5,2) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=25 DEFAULT CHARSET=utf8;

CREATE TABLE `teacher` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `course` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `tid` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `score` (
  `sid` int(11) NOT NULL,
  `cid` int(11) NOT NULL,
  `score` float(5,2) DEFAULT NULL,
  PRIMARY KEY (`sid`,`cid`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

添加学生表数据

存储过程，添加 学生表（student）

DELETE FROM student;
ALTER TABLE student AUTO_INCREMENT = 1;


DROP TABLE IF EXISTS temp_stu;
CREATE TEMPORARY TABLE temp_stu(
    name VARCHAR(255)
);

INSERT INTO `temp_stu` (`name`) VALUES ('张三'),('李四'),('王五'),('赵六'),('牛金霞'),('闫景立'),('孙浩'),('周莉'),('吴鹏'),('郑洁'),('陈婷婷'),('刘洋'),('高敏'),('黄磊'),('林静'),('郭涛'),('何婉如'),('梁志远'),('罗芳芳'),('谢霆锋'),('唐嫣'),('韩雪'),('冯小刚'),('程思远');


DROP PROCEDURE IF EXISTS insert_student_records;

DELIMITER //

CREATE PROCEDURE insert_student_records()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE student_name VARCHAR(255);
    DECLARE student_sex ENUM('female', 'male');
    DECLARE random_year INT;
    DECLARE random_month INT;
    DECLARE random_day INT;
    DECLARE days_in_month INT;
		DECLARE credit FLOAT(5,2);
    
    -- 声明游标
    DECLARE nameset CURSOR FOR SELECT name FROM temp_stu;
    -- 声明继续处理程序
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    
    OPEN nameset;
    
    read_loop: LOOP
        FETCH nameset INTO student_name;
        IF done THEN
            LEAVE read_loop;
        END IF;
        
	
        SET student_sex = IF(RAND() < 0.5, 'female', 'male');
        
        -- 随机选择一个年份（1994, 1995, 1997, 1998, 1999）
        SET random_year = FLOOR(1 + RAND() * 5) + 1993; 
				
				IF random_year = 1996 THEN
            SET random_year = CASE FLOOR(RAND() * 4) + 1994 WHEN 1996 THEN 1994 + FLOOR(RAND() * 4) ELSE random_year - 1 END; 
				END IF;
        
        SET random_month = FLOOR(1 + RAND() * 12);
        
        -- 计算该月的天数（考虑闰年）
        SET days_in_month = CASE
            WHEN (random_month = 2 AND (random_year % 4 = 0 AND (random_year % 100 != 0 OR random_year % 400 = 0))) THEN 29
            WHEN random_month IN (4, 6, 9, 11) THEN 30
            ELSE 31
        END;
        
        SET random_day = FLOOR(1 + RAND() * days_in_month);
        
        SET @birth_date = CONCAT(random_year, '-', LPAD(random_month, 2, '0'), '-', LPAD(random_day, 2, '0'));
				
				SET credit = CASE 
						WHEN RAND() < 0.1 THEN 50 - 30 * RAND() 
						WHEN RAND() < 0.7 THEN 50 + 30 * RAND()
						ELSE 80 + 20 * RAND()	
				END;
 
        
        -- 插入到student表
        INSERT INTO student(name, sex, birth, credit) VALUES(student_name, student_sex, @birth_date, ROUND(credit, 2));
        
    END LOOP;
    
    CLOSE nameset;

END //

DELIMITER ;

-- SHOW CREATE PROCEDURE insert_student_records;
CALL insert_student_records();

DROP PROCEDURE IF EXISTS insert_student_records;
SELECT * FROM student;

其他表

-- 清理环境
DELETE FROM course;
DELETE FROM teacher;
DELETE FROM score;
DROP PROCEDURE IF EXISTS insert_course_records;
DROP PROCEDURE IF EXISTS insert_teacher_records;
DROP PROCEDURE IF EXISTS insert_score_records;

DROP TABLE IF EXISTS temp_course;
CREATE TEMPORARY TABLE temp_course (
    value VARCHAR(255)
);

-- 插入数据到临时表
INSERT INTO temp_course (value) VALUES ('语文'), ('数学'), ('英语'), ('政治'), ('地理'), ('历史'), ('物理'), ('化学'), ('生物'), ('C++'), ('Python'), ('机器学习'), ('强化学习'), ('自然语言处理'), ('关联规则挖掘');


DROP TABLE IF EXISTS temp_teacher;
CREATE TEMPORARY TABLE temp_teacher (
    value VARCHAR(255)
);

-- 插入数据到临时表
INSERT INTO temp_teacher (value) VALUES ('李明'), ('王芳'), ('张伟'), ('赵敏'), ('刘洋'), ('陈静'), ('周杰'), ('孙磊'),('徐丽'), ('朱强'), ('邓敏'), ('韩雪');



DELIMITER //

CREATE PROCEDURE insert_course_records()
BEGIN
		DECLARE done INT DEFAULT FALSE;
		DECLARE course_id INT DEFAULT 1;
		DECLARE course_name VARCHAR(255);
		DECLARE course_num	INT DEFAULT 15;
		DECLARE teacher_num INT DEFAULT 12;
		
		
		-- 声明游标
    DECLARE courseset CURSOR FOR SELECT value FROM temp_course;
    -- 声明继续处理程序
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
		
		
		OPEN courseset;
    
    read_loop: LOOP
        FETCH courseset INTO course_name;
        IF done THEN
            LEAVE read_loop;
        END IF;
				
			SET @teacher_id = CEILING(teacher_num * RAND());
			
			INSERT INTO course(id, name, tid) VALUES(course_id, course_name, @teacher_id);
			
			SET course_id = course_id +1;
			
			END LOOP read_loop;
			
			CLOSE courseset;
	
	
END //


CREATE PROCEDURE insert_teacher_records()
BEGIN
		DECLARE done INT DEFAULT FALSE;
		DECLARE teacher_id INT DEFAULT 1;
		DECLARE teacher_name VARCHAR(255);
		
		DECLARE teacherset CURSOR FOR SELECT value FROM temp_teacher;
		DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
		
		OPEN teacherset;
    
    read_loop: LOOP
        FETCH teacherset INTO teacher_name;
        IF done THEN
            LEAVE read_loop;
        END IF;
				
				INSERT INTO teacher(id, name) VALUES(teacher_id, teacher_name);
				
				SET teacher_id = teacher_id + 1;
		
		END LOOP read_loop;
		
		CLOSE teacherset;
		
END //



CREATE PROCEDURE insert_score_records()
BEGIN
		DECLARE student_num INT DEFAULT 24;
		DECLARE course_num INT DEFAULT 15;
		
		DECLARE student_id INT DEFAULT 1;
		DECLARE course_id INT DEFAULT 1;
		DECLARE score FLOAT(5,2);
		
		
		WHILE student_id <= student_num DO
				SET @temp_course_num = FLOOR(course_num / 3	* RAND());
				SET @course_idx  = 1;
				WHILE @course_idx <= @temp_course_num DO
						SET course_id = CASE 
								WHEN RAND() < 0.4 THEN  @course_idx
								WHEN RAND() < 0.5 THEN  FLOOR(course_num / 3) + @course_idx
								ELSE FLOOR(course_num	/ 3 * 2) + @course_idx
						END ;
						SET score = CASE
								WHEN RAND() < 0.3 THEN ROUND(50 - 20 * RAND(), 2)
								WHEN RAND() < 0.8 THEN ROUND(50 + 30 * RAND(), 2)
								ELSE ROUND(80 + 20 * RAND(), 2)
						END ;
						INSERT INTO score(sid,cid, score) VALUES(student_id, course_id, score);
						SET @course_idx = @course_idx + 1; 
				END WHILE;
				SET student_id = student_id + 1;
		END WHILE;
END//


DELIMITER ;



CALL insert_course_records();
CALL insert_teacher_records();
CALL insert_score_records();

DROP PROCEDURE IF EXISTS insert_course_records;
DROP PROCEDURE IF EXISTS insert_teacher_records;
DROP PROCEDURE IF EXISTS insert_score_records;

SELECT * from course;
SELECT * from teacher;
SELECT * FROM score;

查询示例

  • 查询语文成绩比数学成绩高的学生
SELECT id, name, a.score '语文' , b.score '数学' FROM student 
	JOIN (SELECT sid, score FROM score WHERE cid = 1) a on id = a.sid
	JOIN (SELECT sid, score FROM score WHERE cid = 2) b on id = b.sid
	WHERE a.score > b.score;

结果

+----+-----------+--------+--------+
| id | name      | 语文   | 数学   |
+----+-----------+--------+--------+
|  8 | 周莉      |  82.34 |  75.57 |
|  9 | 吴鹏      |  87.00 |  42.97 |
| 10 | 郑洁      |  99.90 |  77.36 |
| 17 | 何婉如    |  58.68 |  51.54 |
| 24 | 程思远    |  82.41 |  65.65 |
+----+-----------+--------+--------+
5 rows in set (0.00 sec)

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