表结构
学生表
CREATE TABLE xsb (
xh INT(3) UNSIGNED PRIMARY KEY AUTO_INCREMENT,
xm VARCHAR(20) NOT NULL,
xb CHAR(5),
jg VARCHAR(50),
nl TINYINT(3) UNSIGNED,
zcrq DATETIME DEFAULT NOW(),
bj VARCHAR(20),
sfzh CHAR(28) UNIQUE KEY
)CHARSET UTF8;
课程表
CREATE TABLE kcb (
kcm VARCHAR(20) NOT NULL,
kch INT(3) UNSIGNED ZEROFILL AUTO_INCREMENT PRIMARY KEY
)CHARSET UTF8;
成绩表
CREATE TABLE cjb(
xh INT(3) UNSIGNED,
kch INT(3) UNSIGNED ZEROFILL,
cj INT UNSIGNED,
FOREIGN KEY (xh) REFERENCES xsb (xh),
FOREIGN KEY (kch) REFERENCES kcb (kch)
)CHARSET UTF8;
表数据
学生表数据
INSERT xsb (xm,xb,jg,nl,zcrq,bj,sfzh) VALUES
(“张三”,“男”,“北京”,26,“1996-9-1 0:00”,“1班”,“110108198509012000”),
(“李四”,“男”,“河北”,20,“1999-9-1 0:00”,“2班”,“223108199012012000”),
(“王三”,“女”,“山东”,28,“2000-9-1 0:00”,“1班”,“36102319851014720X”),
(“张强”,“男”,“北京”,26,“2002-9-1 0:00”,“3班”,“150623198904260000”),
(“刘一志”,“男”,“上海”,23,“1999-9-1 0:00”,“1班”,“23070319860614070X”),
(“马力强”,“男”,“新疆”,20,“1994-9-1 0:00”,“3班”,“610502199201237000”),
(“赵辉”,“男”,“广西”,18,“2009-9-1 0:00”,“2班”,“621100198502217000”),
(“王静”,“女”,“北京”,20,“1991-9-1 0:00”,“2班”,“152528198805132000”),
(“张慧”,“女”,“湖北”,19,“2012-9-1 0:00”,“1班”,“520327198505224000”),
(“刘霞”,“女”,“河南”,28,“1989-9-1 0:00”,“3班”,“370602197608308000”),
(“王虎”,“男”,“新疆”,27,“11985-9-1 0:00”,“1班”,“652923197506026000”),
(“张三四”,“男”,“北京”,29,“2000-9-1 0:00”,“3班”,“371422199407106000”),
(“郑茜”,“女”,“上海”,22,“2014-9-1 0:00”,“2班”,“360281197504272000”),
(“刘丽”,“女”,“河北”,19,“1996-9-1 0:00”,“1班”,“522601198001260000”),
(“郑志强”,“男”,“山东”,21,“1996-9-1 0:00”,“1班”,“440511199308168000”),
(“何野”,“女”,“河北”,25,“1997-9-1 0:00”,“2班”,“51070319860323170X”),
(“贾强业”,“男”,“河南”,18,“2002-9-1 0:00”,“3班”,“43081119820706786X”),
(“刘贤”,“女”,“山西”,20,“2009-9-1 0:00”,“1班”,“410203198311308000”),
(“刘艳丽”,“女”,“北京”,24,“1996-9-1 0:00”,“3班”,“110105199901012000”),
(“李华强”,“男”,“山西”,22,“1994-9-1 0:00”,“1班”,“510923197712016000”);
课程表数据
INSERT kcb VALUES
(“高等数学”,1),
(“数据库技术”,2),
(“测试管理”,3),
(“Linux基础”,4),
(“自动化简介”,5)
成绩表数据
INSERT cjb VALUES
(1,001,90),
(1,002,60),
(1,003,77),
(1,004,87),
(1,005,50),
(2,001,22),
(2,002,65),
(2,003,100),
(2,004,70),
(2,005,60),
(3,001,32),
(3,002,55),
(3,003,40),
(3,004,89),
(3,005,45),
(4,002,70),
(4,003,96),
(4,004,55),
(4,005,70),
(5,001,NULL),
(5,002,20),
(5,003,77),
(5,004,66),
(5,005,80),
(6,001,40),
(6,002,91),
(6,003,70),
(6,004,66),
(6,005,85),
(7,001,60),
(7,002,71),
(7,003,30),
(7,004,96),
(7,005,40),
(8,001,20),
(8,002,70),
(8,004,100),
(8,005,68),
(9,001,33),
(9,002,74),
(9,003,29),
(9,004,69),
(9,005,80),
(10,001,58),
(10,002,60),
(10,003,59),
(10,004,99),
(10,005,93),
(11,001,70),
(11,003,72),
(11,004,66),
(11,005,25),
(12,001,11),
(12,002,50),
(12,003,30),
(12,004,47),
(12,005,NULL),
(13,001,30),
(13,002,60),
(13,003,46),
(13,004,84),
(13,005,90),
(14,002,99),
(14,003,100),
(14,004,58),
(14,005,85),
(15,001,40),
(15,002,96),
(15,003,49),
(15,004,95),
(15,005,100),
(16,001,68),
(16,002,79),
(16,003,NULL),
(16,004,73),
(16,005,30),
(17,001,60),
(17,002,20),
(17,003,85),
(17,004,96),
(17,005,40),
(18,001,91),
(18,002,74),
(18,003,48),
(18,004,96),
(18,005,74),
(19,001,84),
(19,003,NULL),
(19,004,48),
(19,005,84),
(20,001,93),
(20,002,63),
(20,003,85),
(20,004,100),
(20,005,86);
命令练习
SELECT * FROM xsb
#查询学生信息表 查询学生张三的全部基本信息
SELECT * FROM xsb WHERE xm=‘张三’;
#查询学生张三或李四的基本信息
SELECT * FROM xsb WHERE xm=‘张三’ OR xm=‘李四’;
#查询姓张的学生姓名、班级、年龄
SELECT xm,bj,nl FROM xsb WHERE xm LIKE ‘张%’;
SELECT xm,bj,nl FROM xsb WHERE xm LIKE ‘张_’;
SELECT xm,bj,nl FROM xsb WHERE xm REGEXP ‘[张李王]三’;
#查询学生信息表，姓名中含有四的学生基本信息
SELECT*FROM xsb WHERE xm LIKE ‘%四%’;
#查询学生信息表，姓名长度为三个字，姓李，且最后一个字是 强 字的全部学生学号，姓名，年龄，班级，身份证号码
SELECT xh,xm,nl,bj,sfzh FROM xsb WHERE xm LIKE ‘李_强’;
#查询姓张或者姓李的学生基本信息
SELECT *FROM xsb WHERE xm REGEXP ‘[张李]’;
SELECT * from xsb WHERE xm LIKE ‘张%’ OR xm LIKE ‘李%’;
#查询姓张且在北京的学生信息
SELECT * FROM xsb WHERE xm LIKE ‘张%’ AND jg = ‘北京’;
#查询所属省份是北京 新疆 山东 或者上海的学生信息
SELECT * FROM xsb WHERE jg=‘北京’ OR jg=‘新疆’ OR jg=‘山东’ OR jg=‘上海’;
SELECT * FROM xsb WHERE jg in(‘北京’,‘新疆’,‘山东’,‘上海’);
#查询姓张，但是所属省份不是北京的学生信息
SELECT * FROM xsb WHERE xm LIKE’张%’ AND jg!=‘北京’;
SELECT * FROM xsb WHERE xm LIKE’张%’ AND jg not in (‘北京’);
#查询不是姓张的，且所属省份是河北的学生信息
SELECT * FROM xsb WHERE xm NOT LIKE ‘张%’ AND jg=‘河北’;
#查询所属省份不是北京 新疆 山东 上海的学生信息
SELECT * FROM xsb WHERE jg NOT IN (‘北京’,‘新疆’,‘山东’,‘上海’);
#查询现有的学生都来自于哪些不同的省份
SELECT xm,jg FROM xsb ORDER BY jg ;
SELECT xm,jg FROM xsb GROUP BY xm;
#统计学生信息表 ，共有多少个学生
SELECT COUNT(distinct xm) FROM xsb;
#统计年龄大于20岁的学生共有多少个
SELECT COUNT(nl) FROM xsb WHERE nl > 20;
#注册日期在1998到2000年的学生人数
SELECT COUNT(*) FROM xsb WHERE zcrq > ‘1998-01-01 00:00:00’ AND zcrq < ‘2000-12-31 23:59:59’;
#统计学号为001的学生的平均成绩
SELECT * FROM cjb;
SELECT xh,AVG(cj) FROM cjb WHERE xh=1;
#学号为001的学生总成绩
SELECT SUM(cj) FROM cjb WHERE kch = 001;
#查询课程号为001的课程最高成绩
SELECT MAX(cj) FROM cjb;
#查询所有学生 中最大年龄是多少
SELECT MAX(nl) FROM xsb;
#查询全部学生信息，并按照性别排序
SELECT * FROM xsb ORDER BY xb;
#查询没有填写成绩的学生学号，课程号和成绩，并按照学号升序排序
SELECT * FROM cjb WHERE cj IS NULL ORDER BY xh;
#查询填写成绩的选修信息，按照成绩从高到低排序
SELECT * FROM cjb WHERE cj IS NOT NULL ORDER BY cj DESC;
#统计每个课程的选修人数
SELECT kch,COUNT(kch) FROM cjb GROUP BY kch;
#统计每个同学的总成绩和学号
SELECT xh,SUM(cj) FROM cjb GROUP BY xh;
#统计每个班级每种性别的学生人数，按照班级排序
SELECT SUM(CASE WHEN xb=‘男’ THEN 1 ELSE 0 END ) AS 男,sum(CASE WHEN xb=‘女’ THEN 1 ELSE 0 END ) AS 女,bj FROM xsb GROUP BY bj;
#统计每个课程的平均成绩，按照平均成绩降序排序
SELECT kch,AVG(cj) FROM cjb GROUP BY kch ORDER BY AVG(cj) DESC;
#显示有两门以上课程不及格的学生学号
SELECT COUNT(xh) as qqq,xh FROM cjb WHERE cj<60 GROUP BY xh HAVING qqq>=2;
#统计每个班级中最大年龄是多少
SELECT bj,MAX(nl) FROM xsb GROUP BY bj;