题目
查询学生姓名、生日以及截至 2025-03-12 的周岁。
知识点：日期差、CASE
运行环境：本站提供 SQLite 环境，下面脚本可直接运行。若使用 MySQL，见文中对照；有差异的题目会同时给出 MySQL 写法。
思路
周岁不是直接用年份相减。先算年份差，若 2025-03-12 还没到生日的月日，再减一岁。
MySQL 可用 TIMESTAMPDIFF(YEAR, birthday, '2025-03-12')。基准日写死，才能和示例对拍。
MySQL 与 SQLite 对照
| 场景 | MySQL | SQLite |
|---|---|---|
| 日期间隔天数 | DATEDIFF(sold_on, joined_on) | CAST(JULIANDAY(sold_on) - JULIANDAY(joined_on) AS INT) |
| 年龄（整岁） | TIMESTAMPDIFF(YEAR, birthday, '2025-03-12') | CAST(STRFTIME('%Y', '2025-03-12') AS INT) - CAST(STRFTIME('%Y', birthday) AS INT) - CASE WHEN STRFTIME('%m-%d', '2025-03-12') < STRFTIME('%m-%d', birthday) THEN 1 ELSE 0 END |
SQLite 解法
-- 第64题：查询截至 2025-03-12 的学生周岁
-- 样例数据：学生选课 + 员工部门。最后一条 SELECT 为本题查询。
DROP TABLE IF EXISTS score;
DROP TABLE IF EXISTS course;
DROP TABLE IF EXISTS student;
DROP TABLE IF EXISTS teacher;
DROP TABLE IF EXISTS emp;
DROP TABLE IF EXISTS dept;
CREATE TABLE teacher (
tid TEXT PRIMARY KEY,
tname TEXT NOT NULL
);
CREATE TABLE student (
sid TEXT PRIMARY KEY,
sname TEXT NOT NULL,
ssex TEXT,
birthday TEXT,
city TEXT,
email TEXT
);
CREATE TABLE course (
cid TEXT PRIMARY KEY,
cname TEXT NOT NULL,
tid TEXT,
credit INTEGER
);
CREATE TABLE score (
sid TEXT,
cid TEXT,
score REAL,
exam_on TEXT
);
CREATE TABLE dept (
did TEXT PRIMARY KEY,
dname TEXT NOT NULL
);
CREATE TABLE emp (
eid TEXT PRIMARY KEY,
ename TEXT NOT NULL,
did TEXT,
manager_id TEXT,
salary INTEGER,
hired_on TEXT
);
INSERT INTO teacher(tid, tname) VALUES
('T01', '何启明'),
('T02', '陆知秋'),
('T03', '裴南'),
('T04', '江衡');
INSERT INTO student(sid, sname, ssex, birthday, city, email) VALUES
('S01', '林晓', '女', '2003-03-12', '杭州', 'linxiao@campus.test'),
('S02', '周衡', '男', '2002-11-08', '宁波', 'zhouheng@campus.test'),
('S03', '沈予', '女', '2003-06-21', '杭州', 'shenyu@campus.test'),
('S04', '韩牧', '男', '2002-07-09', '温州', 'hanmu@campus.test'),
('S05', '叶安', '女', '2004-01-30', '杭州', 'yean@campus.test'),
('S06', '方迟', '男', '2001-12-19', '嘉兴', 'fangchi@campus.test'),
('S07', '苏晚', '女', '2003-09-04', '宁波', 'suwan@campus.test'),
('S08', '程远', '男', '2004-05-17', '杭州', 'chengyuan@campus.test'),
('S09', '顾星', '女', '2002-10-28', '绍兴', 'guxing@campus.test'),
('S10', '梁野', '男', '2001-02-08', '温州', 'liangye@campus.test'),
('S11', '夏禾', '女', '2003-08-16', '杭州', 'xiahe@campus.test'),
('S12', '许川', '男', '2002-04-25', '宁波', 'xuchuan@campus.test'),
('S13', '丁南', '女', '2004-04-18', '杭州', 'dingnan@campus.test'),
('S14', '蔡河', '男', '2001-06-03', '嘉兴', 'caihe@campus.test'),
('S15', '闻青', '女', '2002-08-22', '绍兴', 'wenqing@campus.test'),
('S16', '邱石', '男', '2003-12-01', '宁波', 'qiushi@campus.test');
INSERT INTO course(cid, cname, tid, credit) VALUES
('C01', '数据库原理', 'T02', 4),
('C02', '离散数学', 'T01', 3),
('C03', '操作系统', 'T03', 4),
('C04', '计算机网络', 'T02', 3),
('C05', '编译原理', 'T01', 4),
('C06', '线性代数', 'T03', 3),
('C07', '软件工程', 'T04', 2),
('C08', '人工智能', 'T04', 3),
('C09', '毕业实习', 'T03', 1);
INSERT INTO score(sid, cid, score, exam_on) VALUES
('S01', 'C01', 88, '2025-01-08'),
('S01', 'C02', 76, '2025-01-10'),
('S01', 'C03', 91, '2025-01-12'),
('S01', 'C04', 85, '2025-01-09'),
('S01', 'C05', 72, '2025-01-11'),
('S01', 'C06', 90, '2025-01-13'),
('S01', 'C07', 68, '2025-01-08'),
('S01', 'C08', 80, '2025-02-15'),
('S02', 'C01', 70, '2025-01-08'),
('S02', 'C02', 82, '2025-01-10'),
('S02', 'C03', 64, '2025-01-12'),
('S02', 'C04', 55, '2025-01-09'),
('S03', 'C01', 90, '2025-01-08'),
('S03', 'C02', 90, '2025-01-10'),
('S03', 'C03', 85, '2025-01-12'),
('S03', 'C05', 78, '2025-01-11'),
('S04', 'C01', 45, '2025-01-08'),
('S04', 'C02', 52, '2025-01-10'),
('S04', 'C03', 40, '2025-01-12'),
('S04', 'C04', 0, '2025-01-09'),
('S05', 'C01', 79, '2025-01-08'),
('S05', 'C02', 88, '2025-01-10'),
('S05', 'C03', 70, '2025-01-09'),
('S06', 'C01', 0, '2025-01-08'),
('S06', 'C03', 58, '2025-01-12'),
('S06', 'C06', 41, '2025-01-13'),
('S07', 'C02', 94, '2025-01-10'),
('S07', 'C03', 90, '2025-01-12'),
('S07', 'C07', 88, '2025-01-11'),
('S08', 'C01', 86, '2025-01-08'),
('S08', 'C02', 61, '2025-01-10'),
('S08', 'C03', 73, '2025-01-12'),
('S08', 'C08', 69, '2025-02-15'),
('S09', 'C01', 92, '2025-01-08'),
('S09', 'C03', 81, '2025-01-12'),
('S09', 'C04', 77, '2025-01-09'),
('S10', 'C02', 55, '2025-01-10'),
('S10', 'C03', 47, '2025-01-12'),
('S11', 'C01', 77, '2025-01-08'),
('S11', 'C02', 80, '2025-01-10'),
('S11', 'C03', 79, '2025-01-12'),
('S11', 'C05', 66, '2025-01-11'),
('S12', 'C01', 60, '2025-01-08'),
('S13', 'C02', 84, '2025-01-10'),
('S13', 'C07', 91, '2025-01-11'),
('S14', 'C01', 58, '2025-01-08'),
('S14', 'C06', 73, '2025-01-13'),
('S15', 'C03', 62, '2025-01-12'),
('S15', 'C08', 0, '2025-02-15');
INSERT INTO dept(did, dname) VALUES
('D01', '研发部'),
('D02', '教学部'),
('D03', '市场部');
INSERT INTO emp(eid, ename, did, manager_id, salary, hired_on) VALUES
('E01', '陈省', 'D01', NULL, 18000, '2020-03-01'),
('E02', '吴舟', 'D01', 'E01', 12000, '2022-05-12'),
('E03', '唐宁', 'D01', 'E01', 19000, '2021-08-20'),
('E04', '沈泊', 'D02', 'E01', 15000, '2021-11-04'),
('E05', '齐末', 'D02', 'E04', 9000, '2024-04-01'),
('E06', '米白', 'D03', 'E01', 11000, '2023-02-18'),
('E07', '蓝秋', 'D03', 'E06', 8000, '2024-09-01'),
('E08', '贺川', 'D03', 'E06', 21000, '2022-12-10');
-- 本题查询
SELECT sname, birthday,
CAST(STRFTIME('%Y', '2025-03-12') AS INT) - CAST(STRFTIME('%Y', birthday) AS INT)
- CASE WHEN STRFTIME('%m-%d', '2025-03-12') < STRFTIME('%m-%d', birthday) THEN 1 ELSE 0 END AS age
FROM student ORDER BY sid;
MySQL 解法
查询部分与 SQLite 的差异如下（建表请改用 VARCHAR / DECIMAL / DATE）。
SELECT sname, birthday, TIMESTAMPDIFF(YEAR, birthday, '2025-03-12') AS age FROM student ORDER BY sid;运行示例
sname | birthday | age
------+------------+----
林晓 | 2003-03-12 | 22
周衡 | 2002-11-08 | 22
沈予 | 2003-06-21 | 21
韩牧 | 2002-07-09 | 22
叶安 | 2004-01-30 | 21
方迟 | 2001-12-19 | 23
苏晚 | 2003-09-04 | 21
程远 | 2004-05-17 | 20
顾星 | 2002-10-28 | 22
梁野 | 2001-02-08 | 24
夏禾 | 2003-08-16 | 21
许川 | 2002-04-25 | 22
丁南 | 2004-04-18 | 20
蔡河 | 2001-06-03 | 23
闻青 | 2002-08-22 | 22
邱石 | 2003-12-01 | 21