Mysql 实例：mysql语句练习50题（sqlalchmy写法）

为了练习sql语句,在网上找了一些题,自己做了一遍,收益颇多.很多地方换一种思路,有更好的写法,欢迎指正.

题目地址:https://blog.csdn.net/fashion2014/article/details/78826299 ,他有更好的写法

参考视频 https://www.bilibili.com/video/BV1q4411G7Lw?p=1

表名和字段

–1.学生表
Student(id,name,birth,sex) –学生编号,学生姓名, 出生年月,学生性别
–2.课程表
Course(id,name) – –课程编号, 课程名称
–3.教师表
Teacher(id,name,cou_id) –教师编号,教师姓名,课程id
–4.成绩表
Score(id,score,stu_id,cou_id) –成绩编号，分数，学生编号,课程编号

建表

from sqlalchemy import create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column,Integer,String,ForeignKey,DateTime

from sqlalchemy.orm import relationship,sessionmaker

engine = create_engine(

        "mysql+pymysql://root:123456@localhost:3306/school?charset=utf8",

        max_overflow=20,

        pool_size=5,

        pool_timeout=30,

        pool_recycle=20

        )

Base = declarative_base()

#class Stu2Course(Base):

#    __tablename__ = "student_course"

#    id = Column(Integer,primary_key=True,autoincrement=True)

#    stu_id = Column(Integer,ForeignKey("student.id"))

#    course_id = Column(Integer,ForeignKey("course.id"))

#class Stu2Teacher(Base):

#    __tablename__ = "student_teacher"

#    id = Column(Integer,primary_key=True,autoincrement=True)

#    stu_id = Column(Integer,ForeignKey("student.id"))

#    tea_id = Column(Integer,ForeignKey("teacher.id"))

class Stu(Base):

    __tablename__ = "student"

    id = Column(Integer,primary_key=True)

    name = Column(String(32),nullable=False)

    birth = Column(String(32),nullable=False)

    sex = Column(String(5),nullable=False)

    grades = relationship("Grade",backref="student")

    #courses = relationship("Course",secondary="Stu2Course",backref="student")

   # teachers = relationship("Teacher",secondary="Stu2Teacher",backref="student")

class Course(Base):

    __tablename__ = "course"

    id = Column(Integer,primary_key=True)

    name = Column(String(32),nullable=False)

    grades = relationship("Grade",backref="course")

    teachers = relationship("Teacher",backref="teacher")

class Teacher(Base):

    __tablename__ = "teacher"

    id = Column(Integer,primary_key=True)

    name = Column(String(32),nullable=False)

    cou_id = Column(Integer,ForeignKey("course.id"))

class Grade(Base):

    __tablename__ = "grade"

    id = Column(Integer,primary_key=True)

    score = Column(Integer,nullable=False)

    stu_id = Column(Integer,ForeignKey("student.id"))

    cou_id = Column(Integer,ForeignKey("course.id"))

Session = sessionmaker(bind=engine)

session = Session()

if __name__ == "__main__":

    Base.metadata.create_all(engine)

    #Base.metadata.drop_all(engine)

插入数据

#学生表

insert into student values('' , '赵雷' , '1990-01-01' , '男');

insert into student values('' , '钱电' , '1990-12-21' , '男');

insert into student values('' , '孙风' , '1990-05-20' , '男');

insert into student values('' , '李云' , '1990-08-06' , '男');

insert into student values('' , '周梅' , '1991-12-01' , '女');

insert into student values('' , '吴兰' , '1992-03-01' , '女');

insert into student values('' , '郑竹' , '1989-07-01' , '女');

insert into student values('' , '王菊' , '1990-01-20' , '女');

#课程表

insert into course values('' , '语文');

insert into course values('' , '数学');

insert into course values('' , '英语');

#教师表

insert into teacher values('' , '张三','');

insert into teacher values('' , '李四','');

insert into teacher values('' , '王五','');

#成绩表

insert into grade values(1,80,'' , '');

insert into grade values(2,90,'' , '');

insert into grade values(3,99,'' , '');

insert into grade values(4,70,'' , '');

insert into grade values(5,60,'' , '');

insert into grade values(6,80,'' , '');

insert into grade values(7,80,'' , '');

insert into grade values(8,80,'' , '');

insert into grade values(9,80,'' , '');

insert into grade values(10,50,'' , '');

insert into grade values(11,30,'' , '');

insert into grade values(12,20,'' , '');

insert into grade values(13,76,'' , '');

insert into grade values(14,87,'' , '');

insert into grade values(15,31,'' , '');

insert into grade values(16,34,'' , '');

insert into grade values(17,89,'' , '');

insert into grade values(18,98,'' , '');

练习题和sql语句

#1 查询01课程比02课程成绩高的学生的信息以及课程分数

# 找出课程为01的学生的学生信息以及成绩

# 找出课程为02的学生的学生信息以及成绩

data_1 = session.query(Grade.stu_id,Grade.cou_id,Grade.score).filter(Grade.cou_id==1).subquery()

data_2 = session.query(Grade.stu_id,Grade.cou_id,Grade.score).filter(Grade.cou_id==2).subquery()

data_3 = session.query(data_1.c.stu_id).filter(data_1.c.stu_id==data_2.c.stu_id,data_1.c.score>data_2.c.score).subquery()

#学生信息

data_4 = session.query(Stu).filter(Stu.id == data_3.c.stu_id).all()

#课程分数

data_5  = session.query(Stu.name,data_1.c.stu_id,data_1.c.score,data_2.c.score).filter(

        data_1.c.stu_id==data_2.c.stu_id,

        data_1.c.score>data_2.c.score,

        Course.id==data_1.c.cou_id,

        Stu.id == data_1.c.stu_id,

        ).all()

print([v for v in data_5])

#2 查询平均值大于等于60分的同学的学生编号和学生成绩
from sqlalchemy.sql import func

#data = session.query(Stu.id,Stu.name,func.avg(Grade.score)).join(
# Stu
# ).filter(
# Stu.id ==Grade.stu_id

# ).group_by(Grade.stu_id).having(func.avg(Grade.score)>=60).all()

#print([v for v in data])

#3、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
#data = session.query(Stu.id,Stu.name,func.count(Grade.stu_id),func.sum(Grade.score)).join(

# Stu
# ).filter(
# Stu.id ==Grade.stu_id

# ).group_by(Grade.stu_id).all()

#print([v for v in data])

#4、查询"李"姓老师的数量
#data = session.query(Teacher.id,Teacher.name,).filter(Teacher.name.like("李%")).all()

#print([v for v in data])

#5、查询学过"张三"老师授课的同学的信息
#data_1 = session.query(Teacher.cou_id).filter(Teacher.name=="张三").subquery()

#data = session.query(Stu.id).filter(Stu.id==Grade.stu_id,Grade.cou_id==data_1.c.cou_id).all()

#print([v for v in data])

#6、查询没学过"张三"老师授课的同学的信息
from sqlalchemy import not_,and_
#data_1 = session.query(Teacher.cou_id).filter(Teacher.name=="张三").subquery()

#data_2 = session.query(Stu.id).filter(Stu.id==Grade.stu_id,Grade.cou_id==data_1.c.cou_id).all()

#data = session.query(Stu.id).filter(Stu.id.notin_([v[0] for v in data_2])).all()

#print([v[0] for v in data])

#7、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息

#data_1 = session.query(Stu.id).join(Grade).filter(Stu.id==Grade.stu_id,Grade.cou_id==1).subquery()

#data_2 = session.query(Stu.id).join(Grade).filter(Stu.id==Grade.stu_id,Grade.cou_id==2).subquery()

#data = session.query(Stu.id).filter(Stu.id==data_1.c.id,Stu.id==data_2.c.id).all()

#print([v for v in data])

#8、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
#data_1 = session.query(Stu.id).join(Grade).filter(Stu.id==Grade.stu_id,Grade.cou_id==1).all()

#data_2 = session.query(Stu.id).join(Grade).filter(Stu.id==Grade.stu_id,Grade.cou_id==2).all()

#data = session.query(Stu.id).filter(and_(Stu.id.in_([v[0] for v in data_1]),Stu.id.notin_([v[0] for v in data_2]))).all()

#print([v for v in data])

#9、查询没有学全所有课程的同学的信息

#data = session.query(Grade.stu_id).group_by(Grade.stu_id).having(func.count(Grade.cou_id)<3).all()

#print([v for v in data])

#10、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息

#data_1 = session.query(Grade.cou_id).filter(Grade.stu_id==1).subquery()

#data = session.query(Stu.id,Stu.name).join(Grade).filter(Grade.stu_id==Stu.id,Grade.cou_id==data_1.c.cou_id).group_by(Stu.id).all()

#print([v for v in data])

#11、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

#data_1 = session.query(Grade.cou_id).filter(Grade.stu_id==1).all()

#stu_ids = session.query(Stu.id).all()

#for stu_id in stu_ids:
# if stu_id[0] == 1:
# continue
# data_temp = session.query(Grade.cou_id).filter(Grade.stu_id==stu_id[0]).all()

# if data_1 == data_temp:
# data = session.query(Stu.id,Stu.name).filter(Stu.id==stu_id[0]).all()
# print([v for v in data])

#12、查询没学过"张三"老师讲授的任一门课程的学生姓名

#data_1 = session.query(Teacher.cou_id).filter(Teacher.name=="张三").subquery()

#data_2 = session.query(Grade.stu_id).filter(Grade.cou_id == data_1.c.cou_id).group_by(Grade.stu_id).all()

#data = session.query(Stu.id,Stu.name).filter(Stu.id.notin_([v[0] for v in data_2])).all()

#print([v for v in data])

#13、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

#data = session.query(Grade.stu_id).filter(Grade.score<60).group_by(Grade.stu_id).having(func.count(Grade.cou_id)>=2).all()

#print([v for v in data])

#14、检索"01"课程分数小于60，按分数降序排列的学生信息

#data = session.query(
# Grade.stu_id,
# func.max(
# case([(Grade.cou_id==1,Grade.score)],else_=0)
# ),
# func.max(
# case([(Grade.cou_id==2,Grade.score)],else_=0)
# ),

# func.max(
# case([(Grade.cou_id==3,Grade.score)],else_=0)
# ),

# func.avg(Grade.score)
# ).group_by(Grade.stu_id).order_by(func.avg(Grade.score).desc()).all()

#print([v for v in data])

#15、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
from sqlalchemy import case

#data = session.query(
# Grade.stu_id,
# func.max(
# case([
# (Grade.cou_id==1,Grade.score)
# ],
# else_=0
# )
# ),

# func.max(
# case([
# (Grade.cou_id==2,Grade.score)
# ],
# else_=0
# )
# ),

# func.max(
# case([
# (Grade.cou_id==3,Grade.score)
# ],
# else_=0
# )
# ),
# func.avg(Grade.score)
# ).group_by(Grade.stu_id).order_by(func.avg(Grade.score).desc()).all()

#print([v for v in data])

#16.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

#data = session.query(
# Grade.cou_id,
# Course.name,
# func.max(Grade.score),
# func.min(Grade.score),
# func.sum(case([(Grade.score>=60,1)],else_=0))/func.count(Grade.stu_id),
# func.sum(case([(Grade.score.in_(range(70,80)),1)],else_=0))/func.count(Grade.stu_id),

# func.sum(case([(Grade.score.in_(range(80,89)),1)],else_=0))/func.count(Grade.stu_id),
# func.sum(case([((Grade.score>=90),1)],else_=0))/func.count(Grade.stu_id),

# ).join(
# Course

# ).filter(
# Grade.cou_id == Course.id
# ).group_by(Grade.cou_id).all()

#print([v for v in data])

# 17、按各科成绩进行排序，并显示排名(实现不完全)
# mysql没有rank函数
# 加@score是为了防止用union all 后打乱了顺序
#data = session.query(func.row_number().over(order_by=Grade.score), Grade.score).filter(Grade.cou_id==1).all()

#print([v for v in data])

# 18、查询学生的总成绩并进行排名
#data = session.query(Grade.stu_id,func.sum(Grade.score).label('total_score'),
# func.row_number().over(order_by=func.sum(Grade.score).label('total_score'))
# ).group_by(Grade.stu_id).order_by(func.sum(Grade.score)).all()

#print([v for v in data])

# 19、查询不同老师所教不同课程平均分从高到低显示

#data = session.query(Grade.cou_id,Course.name,func.avg(Grade.score)).join(
# Course

# ).filter(
# Course.id == Grade.cou_id

# ).group_by(Grade.cou_id).order_by(func.avg(Grade.score)).all()

#print([v for v in data])

#20、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩

#data_1 = session.query(
# Stu.id.label('st_id'),
# Grade.cou_id,
# Course.name,
# Grade.score,
# func.row_number().over(order_by=Grade.score,partition_by=Grade.cou_id).label('m'),

# ).join(Stu,Course).filter(
# Grade.stu_id == Stu.id,
# Course.id == Grade.cou_id
# ).subquery()

#data = session.query(data_1.c.name,data_1.c.st_id,data_1.c.m).filter(data_1.c.m.in_([2,3]) ).all()

#print([v for v in data])

#23、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],[0-60]及所占百分比

#data = session.query(
# Grade.cou_id,
# Course.name,
# func.count(Grade.stu_id),
# func.sum(case([(Grade.score.in_(range(85,100)),1)],else_=0))/func.count(Grade.stu_id),
# func.sum(case([(Grade.score.in_(range(70,85)),1)],else_=0))/func.count(Grade.stu_id),
# func.sum(case([(Grade.score.in_(range(60,70)),1)],else_=0))/func.count(Grade.stu_id),
# func.sum(case([(Grade.score.in_(range(0,60)),1)],else_=0))/func.count(Grade.stu_id),
# ).join(
# Course
# ).filter(
# Course.id == Grade.cou_id
# ).group_by(Grade.cou_id).all()

#print([v for v in data])

# 24、查询学生平均成绩及其名次
#data = session.query(Grade.stu_id,func.avg(Grade.score),
# func.row_number().over(order_by=func.avg(Grade.score))

# ).group_by(Grade.stu_id).all()

#print([v for v in data])

# 25、查询各科成绩前三名的记录
#data_1 = session.query(
# Stu.id.label('st_id'),
# Grade.cou_id,
# Course.name,
# Grade.score,
# func.row_number().over(order_by=Grade.score,partition_by=Grade.cou_id).label('m'),

# ).join(Stu,Course).filter(
# Grade.stu_id == Stu.id,
# Course.id == Grade.cou_id
# ).subquery()

#data = session.query(data_1.c.name,data_1.c.st_id,data_1.c.m).filter(data_1.c.m.in_([1,2,3]) ).all()

#print([v for v in data])

#26、查询每门课程被选修的学生数
#data = session.query(Grade.cou_id,func.count(Grade.stu_id)).group_by(Grade.cou_id).all()

#print([v for v in data])

# 27、查询出只有两门课程的全部学生的学号和姓名
#data = session.query(Stu.name,Stu.id).join(
# Grade
# ).filter(
# Grade.stu_id == Stu.id
# ).group_by(Grade.stu_id).having(func.count(Grade.cou_id)==2).all()

#print([v for v in data])

#28、查询男生、女生人数
#data = session.query(func.count(Stu.id)).group_by(Stu.sex).all()

#print([v for v in data])

#29、查询名字中含有"风"字的学生信息

#data = session.query(Stu.id,Stu.name).filter(Stu.name.like("%风%")).all()

#print([v for v in data])

# 30、查询同名同性学生名单，并统计同名人数

#data = session.query(Stu.name,func.count(1)).group_by(Stu.name,Stu.sex).having(func.count(1)>1).all()

#print([v for v in data])

# 31、查询1990年出生的学生名单
#data = session.query(Stu.name).filter(Stu.birth.like("%1990%")).all()

#print([v for v in data])

#32、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
from sqlalchemy import desc
#data = session.query(Grade.cou_id,Course.name,func.avg(Grade.score)).join(

# Course).filter(
# Grade.cou_id ==Course.id

# ).group_by(Grade.cou_id).order_by(

# desc(func.avg(Grade.score))).order_by(Grade.cou_id).all()

#print([v for v in data])

#33、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

#data = session.query(Grade.stu_id,Stu.name,func.avg(Grade.score)).join(
# Stu

# ).filter(
# Stu.id == Grade.stu_id

# ).group_by(Grade.stu_id).having(
# func.avg( Grade.score)>=85

# ).all()

#print([v for v in data])

#34、查询课程名称为"数学"，且分数低于60的学生姓名和分数
#data_1 = session.query(Course.name,Grade.score,Grade.stu_id).join(Grade).filter(
# Grade.cou_id ==Course.id,
# Course.name == "数学",
# ).subquery()

#data = session.query(data_1.c.name,data_1.c.score,data_1.c.stu_id,Stu.name).join(
# Stu

# ).filter(
# data_1.c.stu_id ==Stu.id,
# data_1.c.score < 60,

# ).all()

#print([v for v in data])

#35、查询所有学生的课程及分数情况:

#data = session.query(
# Grade.stu_id,
# func.max(
# case([
# (Grade.cou_id==1,Grade.score)
# ],
# else_=0
# )
# ),

# func.max(
# case([
# (Grade.cou_id==2,Grade.score)
# ],
# else_=0
# )
# ),

# func.max(
# case([
# (Grade.cou_id==3,Grade.score)
# ],
# else_=0
# )
# ),
# ).group_by(Grade.stu_id).all()

#print([v for v in data])

# 36、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

#data_1 = session.query(Grade.stu_id,Grade.cou_id,Grade.score).filter(
# Grade.score > 70

# ).subquery()
# 方式一
#data = session.query(Stu.name,Stu.id,Course.name,data_1.c.score).join(
# Course).filter(
# data_1.c.cou_id == Course.id,
# data_1.c.stu_id == Stu.id

# ).all()

#方式二
#data = session.query(

# Stu.name,
# Stu.id,
# func.max(case([(data_1.c.cou_id==1,data_1.c.score)],else_=0)),
# func.max(case([(data_1.c.cou_id==2,data_1.c.score)],else_=0)),
# func.max(case([(data_1.c.cou_id==3,data_1.c.score)],else_=0)),

# ).filter(data_1.c.stu_id==Stu.id).group_by(data_1.c.stu_id).all()

#print([v for v in data])

#37、查询所有学生的所有不及格的课程并按课程编号降序

#data = session.query(Grade.stu_id,Stu.name,Grade.cou_id,Course.name,Grade.score).join(
# Stu,Course).filter(
# Stu.id == Grade.stu_id,
# Grade.cou_id == Course.id,
# Grade.score < 60 ,
# ).order_by(desc(Grade.cou_id)).all()

#print([v for v in data])

#38、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
#data = session.query(Grade.stu_id,Stu.name,Grade.score).join(
# Stu
# ).filter(
# Grade.stu_id == Stu.id,
# Grade.score >= 80,
# Grade.cou_id == 1,

# ).all()

#print([v for v in data])

#39、求每门课程的学生人数
#data = session.query(Grade.cou_id,Course.name,func.count(Grade.stu_id)).join(Course).filter(
# Course.id == Grade.cou_id

# ).group_by(Grade.cou_id).all()

#print([v for v in data])

#40、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
#data_1 = session.query(Teacher.cou_id).filter(Teacher.name == "张三").subquery()
#data_2 = session.query(Grade.stu_id,Grade.score,Grade.cou_id).filter(Grade.cou_id==data_1.c.cou_id).subquery()

#data_3 = session.query(
# Stu.id,
# Stu.name,
# data_2.c.score,
# Course.name.label('cou_name'),
# func.row_number().over(order_by=-data_2.c.score,partition_by=Course.name,).label('m'),
# ).join(
# Course
# ).filter(
# data_2.c.stu_id== Stu.id,
# Course.id == data_2.c.cou_id
# ).subquery()

#data = session.query(data_3.c.name,data_3.c.id,data_3.c.cou_name).filter(data_3.c.m.in_([1]) ).all()

#print([v for v in data])

#41、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

#data_1 = session.query(Grade.stu_id,Grade.score).group_by(Grade.stu_id,Grade.score).subquery()

#data_2 = session.query(data_1.c.stu_id.label('m')).group_by(data_1.c.stu_id).having(func.count(data_1.c.stu_id)<2).subquery()

#data = session.query(Grade.score,Grade.stu_id).filter(Grade.stu_id==data_2.c.m).group_by(Grade.stu_id).having(func.count(Grade.cou_id)>1).all()

#print([v for v in data])

# 42、查询每门功成绩最好的前两名

#data_1 = session.query(
# Stu.id.label('st_id'),
# Grade.cou_id,
# Course.name,
# Grade.score,
# func.row_number().over(order_by=Grade.score,partition_by=Grade.cou_id).label('m'),

# ).join(Stu,Course).filter(
# Grade.stu_id == Stu.id,
# Course.id == Grade.cou_id
# ).subquery()

#data = session.query(data_1.c.name,data_1.c.st_id,data_1.c.m).filter(data_1.c.m.in_([1,2]) ).all()

#print([v for v in data])

#43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，

#data_1 = session.query(Grade.cou_id,func.count(Grade.stu_id).label('s_count')).group_by(Grade.cou_id).having(func.count(Grade.stu_id)>5).subquery()

#data = session.query(Course.id,Course.name,data_1.c.s_count).filter(Course.id==data_1.c.cou_id).order_by(desc(

#data_1.c.s_count
# )).order_by(Course.id).all()

#print([v for v in data])

#44、检索至少选修两门课程的学生学号
#data = session.query(Grade.stu_id).group_by(Grade.stu_id).having(func.count(Grade.cou_id)>=2).all()

#print([v for v in data])

#45、查询选修了全部课程的学生信息

#data = session.query(Grade.stu_id,Stu.name).join(Stu).filter(
# Grade.stu_id == Stu.id

# ).group_by(Grade.stu_id).having(func.count(Grade.cou_id)==3).all()

#print([v for v in data])

#46、查询各学生的年龄
#data = session.query(Stu.id,Stu.birth,func.datediff("2020-03-31",Stu.birth)/365).all()

#print([v for v in data])

#47、查询本周过生日的学生
# 放到同一年进行比较
import time,datetime

#day = datetime.date(2020,3,31).weekday() #0-6 表示星期一到星期天
#gap_day = 7-day
#print(gap_day)
#import re
#data = session.query(Stu.id,Stu.name

# ).filter(

# func.abs(func.datediff('2020-03-31',func.concat('2020-',func.substring(Stu.birth,6,5))))<gap_day
# ).all()

#print([v for v in data])

#48、查询下周过生日的学生

#data = session.query(Stu.id,Stu.name

# ).filter(

# func.abs(func.datediff('2020-03-31',func.concat('2020-',func.substring(Stu.birth,6,5))))<gap_day
# ).all()

#print([v for v in data])

#49、查询本月过生日的学生

#data = session.query(Stu.id,Stu.name

# ).filter(
# func.month(func.now())== func.month(Stu.birth)

# ).all()

#print([v for v in data])

#50、查询下月过生日的学生

data = session.query(Stu.id,Stu.name

).filter(
case([(func.month(func.now())==12,func.month(Stu.birth)==1)],else_=(func.month(func.now())==func.month(Stu.birth)+1))

).all()

print([v for v in data])

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