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经典SQL练习题50道

news 来源：原创 2025/5/16 7:19:38

1.数据表介绍

1.1学生表

Student(SId, Sname, Sage, Ssex)
# SId 学生编号，Sname 学生姓名，Sage 出生年月，Ssex学生性别

1.2课程表

Course(CId, Cname, TId)
# CId 课程编号，Cname 课程名称，TId 教师编号

1.3教师表

Teachaer(TId, Tname)
# TId 教师编号，Tname 教师姓名

1.4成绩表

SC(SId, CId, score)
# SId 学生编号，CId 课程编号，score 分数

2.各表的创建与数据的插入

2.1学生表的创建与数据的插入

# Student表创建
create table Student(
    SId varchar(10),
    Sname varchar(10),
    Sage datetime,
    Ssex varchar(10)
);

# 插入数据
insert into Student values("01", "赵雷", "1990-01-01", "男");
insert into Student values("02", "钱电", "1990-12-21", "男");
insert into Student values("03", "孙风", "1990-12-20", "男");
insert into Student values("04", "李云", "1990-12-06", "男");
insert into Student values("05", "周梅", "1991-12-01", "女");
insert into Student values("06", "吴兰", "1992-01-01", "女");
insert into Student values("07", "郑竹", "1989-01-01", "女");
insert into Student values("09", "张三", "2017-12-20", "女");
insert into Student values("10", "李四", "1017-12-25", "女");
insert into Student values("11", "李四", "2012-06-06", "女");
insert into Student values("12", "赵六", "2013-06-13", "女");
insert into Student values("13", "孙七", "2014-06-01", "女");

2.2 课程表的创建与数据的插入

# Course表的创建
create table Course(
    CId varchar(10),
    Cname varchar(10),
    TId varchar(10)
);

# 插入数据
insert into Course values("01", "语文", "02"); 
insert into Course values("02", "数学", "01"); 
insert into Course values("03", "英语", "03");

2.3教师表的创建与数据的插入

# Course表的创建
create table Course(
    CId varchar(10),
    Cname varchar(10),
    TId varchar(10)
);

# 插入数据
insert into Course values("01", "语文", "02"); 
insert into Course values("02", "数学", "01"); 
insert into Course values("03", "英语", "03");

2.4成绩表的创建与数据的插入

# SC表的创建
create table SC(
    SId varchar(10),
    CId varchar(10),
    score decimal(18, 1)
);

# 插入数据
insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);

3.练习题目

3.1查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数

SELECT 
    s.*,
    sc1.score AS Course01_Score, 
    sc2.score AS Course02_Score
FROM 
    Student s
JOIN 
    (SELECT SId, score FROM SC WHERE CId = '01') sc1 ON s.SId = sc1.SId
JOIN 
    (SELECT SId, score FROM SC WHERE CId = '02') sc2 ON s.SId = sc2.SId
WHERE 
    sc1.score > sc2.score;

构建查询：

子查询：
- 从 SC 表中分别提取出“01”课程和“02”课程的成绩信息，按学生ID分组。
- 可以使用两个子查询，一个选择 CId = '01' 的记录，另一个选择 CId = '02' 的记录。
连接操作：
- 将 Student 表与两个子查询通过 SId 进行连接，确保比较的是同一个学生的成绩。
- 如果 Student 表不存在，可以仅在 SC 表的基础上通过自连接（self-join）实现，但这样将无法获取学生姓名。
条件筛选：
- 使用 WHERE 子句筛选出“01”课程成绩高于“02”课程成绩的学生。

查询结果：

3.1.1查询同时存在" 01 "课程和" 02 "课程的情况

SELECT 
    s.*,
    sc1.score AS Course01_Score, 
    sc2.score AS Course02_Score
FROM 
    Student s
JOIN 
    (SELECT SId, score FROM SC WHERE CId = '01') sc1 ON s.SId = sc1.SId
JOIN 
    (SELECT SId, score FROM SC WHERE CId = '02') sc2 ON s.SId = sc2.SId;

构建查询：

子查询：
- 使用两个子查询分别找出选修了“01”课程和“02”课程的学生ID及其成绩。
- 第一个子查询：SELECT SId, score FROM SC WHERE CId = '01'
- 第二个子查询：SELECT SId, score FROM SC WHERE CId = '02'
连接操作：
- 将 Student 表与两个子查询结果通过 SId 进行连接，确保比较的是同一个学生的信息。
- 可以通过两次自连接 SC 表，或使用两次子查询结果作为派生表进行连接。
条件筛选：
- 确保同一个学生在两个子查询结果中都存在，这可以通过 INNER JOIN 或 EXISTS 等方式隐式实现。
选择字段：
- 选择学生的信息以及两门课程的成绩。

查询结果：

3.1.2查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )

SELECT 
    s.SId, 
    s.Sname, 
    sc01.score AS Course01_Score, 
    sc02.score AS Course02_Score
FROM 
    Student s
LEFT JOIN 
    SC sc01 ON s.SId = sc01.SId AND sc01.CId = '01'
LEFT JOIN 
    SC sc02 ON s.SId = sc02.SId AND sc02.CId = '02'
WHERE 
    sc01.SId IS NOT NULL;

构建查询：

主查询：
- 从 Student 表出发，确保所有选修了“01”课程的学生都被包含在结果集中。
连接“01”课程成绩：
- 使用 LEFT JOIN 将 Student 表与 SC 表连接，筛选出 CId = '01' 的记录，以获取“01”课程的成绩。
连接“02”课程成绩：
- 再次使用 LEFT JOIN 将 Student 表（或上一步的结果集）与 SC 表连接，筛选出 CId = '02' 的记录，以获取“02”课程的成绩。
- 由于是 LEFT JOIN，即使学生未选修“02”课程，其成绩也会显示为 NULL。
选择字段：
- 选择学生的ID、姓名以及两门课程的成绩。

查询结果：

3.1.3查询不存在" 01 "课程但存在" 02 "课程的情况

SELECT 
    s.SId, 
    s.Sname, 
    sc02.score AS Course02_Score
FROM 
    Student s
JOIN 
    SC sc02 ON s.SId = sc02.SId AND sc02.CId = '02'
WHERE 
    NOT EXISTS (
        SELECT 1 
        FROM SC sc01 
        WHERE sc01.SId = s.SId AND sc01.CId = '01'
    );

构建查询：

找出选修了“02”课程的学生：
- 使用子查询或 EXISTS 条件从 SC 表中筛选出选修了“02”课程的学生ID。
排除选修了“01”课程的学生：
- 使用 NOT EXISTS 或 LEFT JOIN 结合 WHERE 子句排除那些同时选修了“01”课程的学生。
连接学生信息：
- 将筛选出的学生ID与 Student 表连接，以获取学生的姓名。
选择字段：
- 选择学生的ID、姓名以及“02”课程的成绩。

查询结果：

3.2查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩

SELECT 
    s.SId, 
    s.Sname, 
    AVG(sc.score) AS AverageScore
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
GROUP BY 
    s.SId, s.Sname
HAVING 
    AVG(sc.score) >= 60;

查询结果：

3.3查询在 SC 表存在成绩的学生信息

SELECT DISTINCT
    s.SId, 
    s.Sname
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId;

查询结果：

3.4查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )

SELECT 
    s.SId, 
    s.Sname, 
    COUNT(sc.CId) AS CourseCount,
    SUM(sc.score) AS TotalScore
FROM 
    Student s
LEFT JOIN 
    SC sc ON s.SId = sc.SId
GROUP BY 
    s.SId, s.Sname;

查询结果：

3.4.1查有成绩的学生信息

SELECT DISTINCT
    s.SId, 
    s.Sname
FROM 
    Student s
INNER JOIN 
    SC sc ON s.SId = sc.SId;

查询结果：

3.5查询「李」姓老师的数量

SELECT COUNT(*) AS LiTeacherCount
FROM Teacher
WHERE Tname LIKE '李%';

查询结果：

3.6查询学过「张三」老师授课的同学的信息

SELECT DISTINCT s.*
FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
JOIN Teacher t ON c.TId = t.TId
WHERE t.Tname = '张三';

查询结果：

3.7查询没有学全所有课程的同学的信息

WITH TotalCourses AS (
    SELECT COUNT(*) AS TotalCourseCount
    FROM Course
),
StudentCourseCounts AS (
    SELECT SId, COUNT(CId) AS SelectedCourseCount
    FROM SC
    GROUP BY SId
)
SELECT s.*
FROM Student s
JOIN StudentCourseCounts scc ON s.SId = scc.SId
JOIN TotalCourses tc ON 1=1
WHERE scc.SelectedCourseCount < tc.TotalCourseCount;

查询结果：

3.8查询至少有一门课与学号为" 01 "的同学所学相同的同学的信

SELECT DISTINCT s.*
FROM Student s
JOIN SC sc ON s.SId = sc.SId
WHERE sc.CId IN (
    SELECT CId
    FROM SC
    WHERE SId = '01'
)
AND s.SId <> '01';

查询结果：

3.9查询和" 01 "号的同学学习的课程完全相同的其他同学的信息

SELECT s.*
FROM Student s
WHERE s.SId <> '01'
AND NOT EXISTS (
    SELECT CId
    FROM SC
    WHERE SId = '01'
    AND CId NOT IN (
        SELECT CId
        FROM SC
        WHERE SId = s.SId
    )
)
AND NOT EXISTS (
    SELECT CId
    FROM SC
    WHERE SId = s.SId
    AND CId NOT IN (
        SELECT CId
        FROM SC
        WHERE SId = '01'
    )
);

查询结果：

3.10查询没学过"张三"老师讲授的任一门课程的学生姓名

SELECT s.Sname
FROM Student s
WHERE s.SId NOT IN (
    SELECT DISTINCT sc.SId
    FROM SC sc
    JOIN Course c ON sc.CId = c.CId
    JOIN Teacher t ON c.TId = t.TId
    WHERE t.Tname = '张三'
);

查询结果：

3.11查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩

SELECT 
    s.SId,
    s.Sname,
    AVG(sc.score) AS 平均成绩
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
WHERE 
    s.SId IN (
        SELECT 
            SId
        FROM 
            SC
        WHERE 
            score < 60
        GROUP BY 
            SId
        HAVING 
            COUNT(*) >= 2
    )
GROUP BY 
    s.SId, s.Sname
ORDER BY 
    s.SId;

查询结果：

3.12检索" 01 "课程分数小于 60，按分数降序排列的学生信息

SELECT s.SId, s.Sname, sc.score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
WHERE sc.CId = '01' AND sc.score < 60
ORDER BY sc.score DESC;

查询结果：

3.13按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩

SELECT 
    s.SId,
    s.Sname,
    -- 动态拼接每个学生的课程成绩
    GROUP_CONCAT(CONCAT(c.Cname, ':', sc.score) ORDER BY c.Cname) AS 所有课程成绩,
    AVG(sc.score) AS 平均成绩
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
JOIN 
    Course c ON sc.CId = c.CId
GROUP BY 
    s.SId, s.Sname
ORDER BY 
    平均成绩 DESC;

查询结果：

3.14查询各科成绩最高分、最低分和平均分：

以如下形式显示：课程 ID，课程 name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率

及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90

要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列

SELECT 
    c.CId,
    c.Cname,
    COUNT(sc.SId) AS 选修人数,
    MAX(sc.score) AS 最高分,
    MIN(sc.score) AS 最低分,
    AVG(sc.score) AS 平均分,
    SUM(CASE WHEN sc.score >= 60 THEN 1 ELSE 0 END) / COUNT(sc.SId) AS 及格率,
    SUM(CASE WHEN sc.score BETWEEN 70 AND 80 THEN 1 ELSE 0 END) / COUNT(sc.SId) AS 中等率,
    SUM(CASE WHEN sc.score BETWEEN 80 AND 90 THEN 1 ELSE 0 END) / COUNT(sc.SId) AS 优良率,
    SUM(CASE WHEN sc.score >= 90 THEN 1 ELSE 0 END) / COUNT(sc.SId) AS 优秀率
FROM 
    Course c
LEFT JOIN 
    SC sc ON c.CId = sc.CId
GROUP BY 
    c.CId, c.Cname
ORDER BY 
    选修人数 DESC, c.CId ASC;

查询结果：

3.15按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺

SELECT 
    CId,
    SId,
    score,
    RANK() OVER (PARTITION BY CId ORDER BY score DESC) AS ranking
FROM 
    SC
ORDER BY 
    CId, ranking;

查询结果：

3.15.1按各科成绩进行排序，并显示排名， Score 重复时合并名次

SELECT 
    CId,
    SId,
    score,
    DENSE_RANK() OVER (PARTITION BY CId ORDER BY score DESC) AS ranking
FROM 
    SC
ORDER BY 
    CId, ranking;

查询结果：

3.16查询学生的总成绩，并进行排名，总分重复时保留名次空缺

SELECT 
    SId,
    SUM(score) AS total_score
FROM 
    SC
GROUP BY 
    SId
ORDER BY 
    total_score DESC;

查询结果：

3.16.1 查询学生的总成绩，并进行排名，总分重复时不保留名次空缺

SELECT 
    SId,
    total_score,
    DENSE_RANK() OVER (ORDER BY total_score DESC) AS ranking
FROM (
    SELECT 
        SId,
        SUM(score) AS total_score
    FROM 
        SC
    GROUP BY 
        SId
) AS subquery;

查询结果：

3.17统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比

SELECT 
    c.CId AS 课程编号,
    c.Cname AS 课程名称,
    -- 统计 [100 - 85] 分数段人数
    SUM(CASE WHEN sc.score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS `[100-85]`,
    -- 计算 [100 - 85] 分数段人数所占百分比
    CONCAT(ROUND(SUM(CASE WHEN sc.score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) / COUNT(sc.SId) * 100, 2), '%') AS `[100-85]百分比`,
    -- 统计 [85 - 70] 分数段人数
    SUM(CASE WHEN sc.score BETWEEN 70 AND 84 THEN 1 ELSE 0 END) AS `[85-70]`,
    -- 计算 [85 - 70] 分数段人数所占百分比
    CONCAT(ROUND(SUM(CASE WHEN sc.score BETWEEN 70 AND 84 THEN 1 ELSE 0 END) / COUNT(sc.SId) * 100, 2), '%') AS `[85-70]百分比`,
    -- 统计 [70 - 60] 分数段人数
    SUM(CASE WHEN sc.score BETWEEN 60 AND 69 THEN 1 ELSE 0 END) AS `[70-60]`,
    -- 计算 [70 - 60] 分数段人数所占百分比
    CONCAT(ROUND(SUM(CASE WHEN sc.score BETWEEN 60 AND 69 THEN 1 ELSE 0 END) / COUNT(sc.SId) * 100, 2), '%') AS `[70-60]百分比`,
    -- 统计 [60 - 0] 分数段人数
    SUM(CASE WHEN sc.score BETWEEN 0 AND 59 THEN 1 ELSE 0 END) AS `[60-0]`,
    -- 计算 [60 - 0] 分数段人数所占百分比
    CONCAT(ROUND(SUM(CASE WHEN sc.score BETWEEN 0 AND 59 THEN 1 ELSE 0 END) / COUNT(sc.SId) * 100, 2), '%') AS `[60-0]百分比`
FROM 
    Course c
JOIN 
    SC sc ON c.CId = sc.CId
GROUP BY 
    c.CId, c.Cname
ORDER BY 
    c.CId;

查询结果：

3.18查询各科成绩前三名的记录

SELECT 
    CId,
    SId,
    score
FROM (
    SELECT 
        CId,
        SId,
        score,
        RANK() OVER (PARTITION BY CId ORDER BY score DESC) AS ranking
    FROM 
        SC
) subquery
WHERE 
    ranking <= 3
ORDER BY 
    CId, ranking;

查询结果：

3.19查询每门课程被选修的学生数

SELECT 
    c.CId,
    c.Cname,
    COUNT(DISTINCT sc.SId) AS 选修学生数
FROM 
    Course c
LEFT JOIN 
    SC sc ON c.CId = sc.CId
GROUP BY 
    c.CId, c.Cname
ORDER BY 
    c.CId;

查询结果：

3.20查询出只选修两门课程的学生学号和姓名

SELECT 
    s.SId,
    s.Sname
FROM 
    Student s
JOIN 
    (
        SELECT 
            SId
        FROM 
            SC
        GROUP BY 
            SId
        HAVING 
            COUNT(CId) = 2
    ) AS subquery ON s.SId = subquery.SId;

查询结果：

3.21查询男生、女生人数

SELECT 
    Ssex,
    COUNT(SId) AS 人数
FROM 
    Student
GROUP BY 
    Ssex;

查询结果：

3.22查询名字中含有「风」字的学生信息

SELECT *
FROM Student
WHERE Sname LIKE '%风%';

查询结果：

3.23查询同名同性学生名单，并统计同名人数

SELECT 
    Sname,
    Ssex,
    COUNT(SId) AS 同名人数
FROM 
    Student
GROUP BY 
    Sname, Ssex
HAVING 
    COUNT(SId) > 1;

查询结果：

3.24查询 1990 年出生的学生名单

SELECT *
FROM Student
WHERE YEAR(Sage) = 1990;

查询结果;

3.25查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列

SELECT 
    c.CId,
    c.Cname,
    AVG(sc.score) AS 平均成绩
FROM 
    Course c
JOIN 
    SC sc ON c.CId = sc.CId
GROUP BY 
    c.CId, c.Cname
ORDER BY 
    平均成绩 DESC, c.CId ASC;

查询结果：

3.26查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩

SELECT 
    s.SId,
    s.Sname,
    AVG(sc.score) AS 平均成绩
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
GROUP BY 
    s.SId, s.Sname
HAVING 
    AVG(sc.score) >= 85
ORDER BY 
    s.SId;

查询结果：

3.27查询课程名称为「数学」，且分数低于 60 的学生姓名和分数

SELECT 
    s.Sname,
    sc.score
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
JOIN 
    Course c ON sc.CId = c.CId
WHERE 
    c.Cname = '数学'
    AND sc.score < 60;

查询结果：

3.28查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）

SELECT 
    s.SId,
    s.Sname,
    c.CId,
    c.Cname,
    sc.score
FROM 
    Student s
LEFT JOIN 
    SC sc ON s.SId = sc.SId
LEFT JOIN 
    Course c ON sc.CId = c.CId
ORDER BY 
    s.SId, c.CId;

查询结果：

3.29查询任何一门课程成绩在 70 分以上的姓名、课程名称和分数

SELECT 
    s.Sname,
    c.Cname,
    sc.score
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
JOIN 
    Course c ON sc.CId = c.CId
WHERE 
    sc.score > 70;

查询结果：

3.30查询不及格的课程

SELECT c.Cname, sc.score
FROM SC sc
JOIN Course c ON sc.CId = c.CId
WHERE sc.score < 60;

查询结果：

3.31查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名

SELECT 
    s.SId,
    s.Sname
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
WHERE 
    sc.CId = '01'
    AND sc.score > 80;

查询结果：

3.32求每门课程的学生人数

SELECT 
    CId,
    COUNT(DISTINCT SId) AS 学生人数
FROM 
    SC
GROUP BY 
    CId;

查询结果：

3.33成绩不重复，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩

SELECT 
    s.SId,
    s.Sname,
    s.Ssex,
    s.Sage,
    sc.score
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
JOIN 
    Course c ON sc.CId = c.CId
JOIN 
    Teacher t ON c.TId = t.TId
WHERE 
    t.Tname = '张三'
ORDER BY 
    sc.score DESC
LIMIT 1;

查询结果：

3.34成绩有重复的情况下，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩

SELECT 
    s.SId,
    s.Sname,
    s.Ssex,
    s.Sage,
    sc.score
FROM 
    Student s
JOIN 
    SC sc ON s.SId = sc.SId
JOIN 
    Course c ON sc.CId = c.CId
JOIN 
    Teacher t ON c.TId = t.TId
WHERE 
    t.Tname = '张三'
    AND sc.score = (
        SELECT 
            MAX(score)
        FROM 
            SC sc_inner
        JOIN 
            Course c_inner ON sc_inner.CId = c_inner.CId
        JOIN 
            Teacher t_inner ON c_inner.TId = t_inner.TId
        WHERE 
            t_inner.Tname = '张三'
    );

3.35查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩

SELECT 
    sc1.SId,
    sc1.CId,
    sc1.score
FROM 
    SC sc1
JOIN 
    SC sc2 ON sc1.SId = sc2.SId AND sc1.CId != sc2.CId AND sc1.score = sc2.score
ORDER BY 
    sc1.SId, sc1.CId;

查询结果：

3.36查询每门功成绩最好的前两名

SELECT 
    SId,
    CId,
    score
FROM (
    SELECT 
        SId,
        CId,
        score,
        RANK() OVER (PARTITION BY CId ORDER BY score DESC) as ranking
    FROM 
        SC
) ranked
WHERE 
    ranking <= 2
ORDER BY 
    CId, ranking;

查询结果：

3.37统计每门课程的学生选修人数（超过 5 人的课程才统计）

SELECT 
    CId,
    COUNT(SId) AS 选修人数
FROM 
    SC
GROUP BY 
    CId
HAVING 
    COUNT(SId) > 5
ORDER BY 
    选修人数 DESC;

查询结果：

3.38检索至少选修两门课程的学生学号

SELECT 
    SId
FROM 
    SC
GROUP BY 
    SId
HAVING 
    COUNT(CId) >= 2;

查询结果：

3.39查询选修了全部课程的学生信息

SELECT 
    s.*
FROM 
    Student s
WHERE 
    NOT EXISTS (
        SELECT 
            1
        FROM 
            Course c
        WHERE 
            NOT EXISTS (
                SELECT 
                    1
                FROM 
                    SC sc
                WHERE 
                    sc.SId = s.SId
                    AND sc.CId = c.CId
            )
    );

查询结果：

3.40查询各学生的年龄，只按年份来算

SELECT 
    SId,
    Sname,
    YEAR(CURRENT_DATE) - YEAR(Sage) AS age
FROM 
    Student;

查询结果：

3.41按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一

SELECT 
    SId,
    Sname,
    -- 使用 CASE 语句判断当前月日与出生月日的关系
    CASE 
        WHEN MONTH(CURRENT_DATE) < MONTH(Sage) OR (MONTH(CURRENT_DATE) = MONTH(Sage) AND DAY(CURRENT_DATE) < DAY(Sage)) 
            THEN YEAR(CURRENT_DATE) - YEAR(Sage) - 1
        ELSE YEAR(CURRENT_DATE) - YEAR(Sage)
    END AS age
FROM 
    Student;

查询结果：

3.42查询本周过生日的学生

SELECT 
    SId,
    Sname,
    Sage
FROM 
    Student
WHERE 
    WEEKOFYEAR(CURRENT_DATE) = WEEKOFYEAR(Sage)
    AND YEAR(CURRENT_DATE) = YEAR(Sage);

查询结果：

3.43查询下周过生日的学生

SELECT 
    SId,
    Sname,
    Sage
FROM 
    Student
WHERE 
    (WEEKOFYEAR(CURRENT_DATE) + 1 = WEEKOFYEAR(Sage) AND YEAR(CURRENT_DATE) = YEAR(Sage))
    OR 
    (WEEKOFYEAR(CURRENT_DATE) = 52 AND WEEKOFYEAR(Sage) = 1 AND YEAR(CURRENT_DATE) + 1 = YEAR(Sage));

查询结果：

3.44查询本月过生日的学生

SELECT 
    SId,
    Sname,
    Sage
FROM 
    Student
WHERE 
    MONTH(CURRENT_DATE) = MONTH(Sage)
    AND YEAR(CURRENT_DATE) = YEAR(Sage);

查询结果：

3.45查询下月过生日的学生

SELECT 
    SId,
    Sname,
    Sage
FROM 
    Student
WHERE 
    (
        -- 正常情况：下个月的月份 = 生日月份，且年份相同
        (MONTH(DATE_ADD(CURRENT_DATE, INTERVAL 1 MONTH)) = MONTH(Sage) 
         AND YEAR(DATE_ADD(CURRENT_DATE, INTERVAL 1 MONTH)) = YEAR(Sage))
        OR 
        -- 跨年情况：当前是 12 月，下个月是 1 月，生日在 1 月且年份为下一年
        (MONTH(CURRENT_DATE) = 12 
         AND MONTH(Sage) = 1 
         AND YEAR(DATE_ADD(CURRENT_DATE, INTERVAL 1 MONTH)) = YEAR(Sage))
    );

查询结果：