温故知新（下）：MySQL vs Python
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问题4：
1.查询选修01课程的学生信息
2.查询选修语文课程的学生信息
3.查询出只选修两门课程的学生学号和姓名
4.查询学生的基本信息以及该生选修了多少门课程
一、mysql方法
SELECT
student.*
FROM student INNER JOIN sc ONstudent.Sno=sc.Sno
INNER JOIN course ON sc.Cno=course.Cno
WHERE course.Cno="01"
SELECT
student.*
FROM student INNER JOIN sc ONstudent.Sno=sc.Sno
INNER JOIN course ON sc.Cno=course.Cno
WHERE course.Cname="语文"
SELECT
student.Sno,
student.Sname
FROM student INNER JOIN sc ONstudent.Sno=sc.Sno
GROUP BY student.Sno, student.Sname
HAVING COUNT(sc.Cno)=2
SELECT
sc.Sno,
COUNT(sc.Cno)AS 课程数
FROM sc
GROUP BY sc.Sno
SELECT
*
FROM student
INNER JOIN new_course onstudent.Sno=new_course.Sno
二、Python方法
import pandas as pd
pd.options.display.max_columns = 999
pd.options.display.max_rows = 999
student = pd.read_excel('C:/Liu/Test/School.xlsx',sheet_name='Student', dtype={'Sno': str, 'Class': str})
teacher =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Teacher', dtype={'Tno':str})
course =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Course', dtype={'Cno':str, 'Tno': str})
score =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='SC', dtype={'Sno': str,'Cno': str})
full = student.merge(score,on='Sno').merge(course, on='Cno')
qT1 =full.query("Cno=='01'")[['Sno', 'Sname', 'Sbirthday', 'Ssex', 'Class']]
print(qT1)
qT2 = full.query("Cname=='语文'")[['Sno', 'Sname', 'Sbirthday', 'Ssex', 'Class']]
print(qT2)
qT3 = full.pivot_table(index=['Sno','Sname'], values='Cno', aggfunc='count').reset_index().query('Cno==2')
print(qT3)
qT4 = full.pivot_table(index=['Sno','Sname', 'Sbirthday', 'Ssex', 'Class'], values='Cno',aggfunc='count').reset_index()
print(qT4)
问题5：
1.查询数学成绩小于60分的记录，字段：学号、姓名、课程号、课程名称、成绩
2.查询学过「张三」老师授课的同学的信息
3.查询没有选修任意一门课程的学生的学号、学生姓名
4.查询李四老师授课课程的最高分、最低分
5.查询同样课程比‘02’号同学成绩高的同学的学号，课程号和分数
一、MySQL方法
SELECT
student.Sno,
student.Sname,
course.Cno,
course.Cname,
sc.Score
FROM student INNER JOIN sc ONstudent.Sno=sc.Sno
INNER JOIN course ON sc.Cno=course.Cno
WHERE course.Cname="数学" AND sc.Score<60
SELECT
student.*
FROM student INNER JOIN sc ONstudent.Sno=sc.Sno
INNER JOIN course ON sc.Cno=course.Cno
INNERJOIN teacher ON course.Tno=teacher.Tno
WHERE teacher.Tname="张三"
SELECT
student.Sno,
student.Sname
FROM student LEFT JOIN sc ONstudent.Sno=sc.Sno
WHERE sc.Cno IS NULL
SELECT
MAX(sc.Score) AS 最高分,
MIN(sc.Score)AS 最低分
FROM sc INNER JOIN course ONsc.Cno=course.Cno
INNER JOIN teacher ON course.Tno=teacher.Tno
WHERE teacher.Tname="李四"
SELECT
*
FROM sc
WHERE sc.Sno="02"
SELECT
*
FROM sc
WHERE sc.Score>(SELECT new_score.ScoreFROM new_score WHERE new_score.Cno=sc.Cno)
二、Python方法
import pandas as pd
pd.options.display.max_columns = 999
pd.options.display.max_rows = 999
student =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Student', dtype={'Sno':str, 'Class': str})
teacher =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Teacher', dtype={'Tno':str})
course =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Course', dtype={'Cno':str, 'Tno': str})
score = pd.read_excel('C:/Liu/Test/School.xlsx',sheet_name='SC', dtype={'Sno': str, 'Cno': str})
full = student.merge(score,on='Sno').merge(course, on='Cno').merge(teacher, on='Tno')
qT1 = full.query("Cname=='数学' & Score<60")[['Sno', 'Sname', 'Cno', 'Cname','Score']].reset_index(drop=True)
print(qT1)
qT2 = full.query("Tname=='张三'")[['Sno', 'Sname', 'Sbirthday', 'Ssex','Class']].reset_index(drop=True)
print(qT2)
qT3 = student.merge(score, how='left',on='Sno')
qT3 = qT3[qT3['Cno'].isnull()][['Sno','Sname']]
print(qT3)
max_sc = full.query("Tname=='李四'")['Score'].max()
min_sc = full.query("Tname=='李四'")['Score'].min()
print(max_sc, min_sc)
temp = score.query("Sno=='02'")
sample = score.merge(temp, how='left',on='Cno')
qT4 = sample[sample['Score_x'] >sample['Score_y']][['Sno_x', 'Cno', 'Score_x']].reset_index(drop=True)
print(qT4)
问题6：
1.查询Student表中'01'班所有学生的基本信息。
2.查询SC表中成绩不及格的所有记录。
3.查询SC表中成绩在70到80之间的所有记录。
4.查询SC表中'01'号课程成绩在70到80之间的所有记录。
5.查询SC表中课程号为'01'或'01'号学生成绩在70到80之间的所有记录。
6.查询Student表中性别未知的学号、姓名。
7.查询Student表中'01'班性别不为空的所有学生基本信息。
8.查询Student表中不姓“周”的同学记录。
9.查询Student表中姓“王”且在“01”班中的同学记录
10.查询SC表里分数为60、70或80的学生的学号、课程号和对应分数。
一、MySQL方法
SELECT
*
FROM student
WHERE student.Class="01"
SELECT
*
FROM sc
WHERE sc.Score<60
SELECT
*
FROM sc
WHERE sc.Score BETWEEN 70 AND 80
SELECT
*
FROM sc
WHERE (sc.Cno="01") AND(sc.Score BETWEEN 70 AND 80)
SELECT
*
FROM sc
WHERE (sc.Cno="01" ORsc.Sno="01") AND (sc.Score BETWEEN 70 AND 80)
SELECT
student.Sno,
student.Sname
FROM student
WHERE student.Ssex="未知"
SELECT
*
FROM student
WHERE student.Class="01" ANDstudent.Ssex IS NOT NULL
SELECT
*
FROM student
WHERE student.Sname NOT LIKE "周%"
SELECT
*
FROM student
WHERE student.Class="01" ANDstudent.Sname LIKE "王%"
SELECT
*
FROM sc
WHERE sc.Score in (60,70,80)
二、Python方法
import pandas as pd
pd.options.display.max_columns = 999
pd.options.display.max_rows = 999
student =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Student', dtype={'Sno':str, 'Class': str})
teacher =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Teacher', dtype={'Tno':str})
course =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='Course', dtype={'Cno':str, 'Tno': str})
score =pd.read_excel('C:/Liu/Test/School.xlsx', sheet_name='SC', dtype={'Sno': str,'Cno': str})
qT1 =student.query("Class=='01'").reset_index(drop=True)
print(qT1)
qT2 =score.query('Score<60').reset_index(drop=True)
print(qT2)
qT3 = score.query('70<=Score<=80').reset_index(drop=True)
print(qT3)
qT4 =score.query("(Cno=='01')&(70<=Score<=80)").reset_index(drop=True)
print(qT4)
qT5 =score.query("((Cno=='01')|(Sno=='01'))&(70<=Score<=80)").reset_index(drop=True)
print(qT5)
qT6 = student[student['Ssex'].isnull()][['Sno','Sname']].reset_index(drop=True)
print(qT6)
qT7 = student[(student['Ssex'].notnull())& (student['Class'] == '01')].reset_index(drop=True)
print(qT7)
qT8 =student[~student['Sname'].str.contains('周')].reset_index(drop=True)
print(qT8)
qT9 =student[(student['Sname'].str.contains('王')) &(student['Class'] == '01')].reset_index(drop=True)
print(qT9)
qT10 = score.query('Score in(60,70,80)').reset_index(drop=True)
print(qT10)
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