2019独角兽企业重金招聘Python工程师标准>>> 
MySQL表的建立
例子：
import MySQLdb
def connect_mysql():
db_config = {
'host': '192.168.48.128',
'port': 3306,
'user': 'xiang',
'passwd': '123456',
'db': 'python',
'charset': 'utf8'
}
cnx = MySQLdb.connect(**db_config)
return cnx
if __name__ == '__main__':
cnx = connect_mysql()
cus = cnx.cursor()
# sql = '''insert into student(id, name, age, gender, score) values ('1001', 'ling', 29, 'M', 88), ('1002', 'ajing', 29, 'M', 90), ('1003', 'xiang', 33, 'M', 87);'''
student = '''create table Student(
StdID int not null,
StdName varchar(100) not null,
Gender enum('M', 'F'),
Age tinyint
)'''
course = '''create table Course(
CouID int not null,
CName varchar(50) not null,
TID int not null
)'''
score = '''create table Score(
SID int not null,
StdID int not null,
CID int not null,
Grade int not null
)'''
teacher = '''create table Teacher(
TID int not null,
TName varchar(100) not null
)'''
tmp = '''set @i := 0;
#mysql中变量不用事前申明，在用的时候直接用“@变量名”使用就可以了。set这个是mysql中设置变量的特殊用法，当@i需要在select中使用的时候，必须加:
create table tmp as select (@i := @i + 1) as id from information_schema.tables limit 10;
'''
try:
cus.execute(student)
cus.execute(course)
cus.execute(score)
cus.execute(thearch)
cus.execute(tmp)
cus.close()
cnx.commit()
except Exception as e:
cnx.rollback()
print('error')
raise e
finally:
cnx.close()
MySQL数据的建立
例子:
import MySQLdb
def connect_mysql():
db_config = {
'host': '192.168.48.128',
'port': 3306,
'user': 'xiang',
'passwd': '123456',
'db': 'python',
'charset': 'utf8'
}
cnx = MySQLdb.connect(**db_config)
return cnx
if __name__ == '__main__':
cnx = connect_mysql()
students = '''set @i := 10000;
#floor()函数表示去尾法取整；rand()函数代表的是从0到1取一个随机的小数；3+floor(rand() * 75)就代表的是：3到77的任意一个数字；concat()函数是一个对多个字符串拼接函数；sha1()是一个加密函数，sha1(rand())对生成的0到1的一个随机小数进行加密，转换成字符串的形式；
insert into Student select @i:=@i+1, substr(concat(sha1(rand()), sha1(rand())), 1, 3 + floor(rand() * 75)), case floor(rand()*10) mod 2 when 1 then 'M' else 'F' end, 25-floor(rand() * 5) from tmp a, tmp b, tmp c, tmp d;
'''
course = '''set @i := 10;
insert into Course select @i:=@i+1, substr(concat(sha1(rand()), sha1(rand())), 1, 5 + floor(rand() * 40)), 1 + floor(rand() * 100) from tmp a;
'''
score = '''set @i := 10000;
insert into Score select @i := @i +1, floor(10001 + rand()*10000), floor(11 + rand()*10), floor(1+rand()*100) from tmp a, tmp b, tmp c, tmp d;
'''
theacher = '''set @i := 100;
insert into Teacher select @i:=@i+1, substr(concat(sha1(rand()), sha1(rand())), 1, 5 + floor(rand() * 80)) from tmp a, tmp b;
'''
try:
cus_students = cnx.cursor()
cus_students.execute(students)
cus_students.close()
cus_course = cnx.cursor()
cus_course.execute(course)
cus_course.close()
cus_score = cnx.cursor()
cus_score.execute(score)
cus_score.close()
cus_teacher = cnx.cursor()
cus_teacher.execute(theacher)
cus_teacher.close()
cnx.commit()
except Exception as e:
cnx.rollback()
print('error')
raise e
finally:
cnx.close()
MySQL数据的查询
例子：
import codecs
import MySQLdb
def connect_mysql():
db_config = {
'host': '192.168.48.128',
'port': 3306,
'user': 'xiang',
'passwd': '123456',
'db': 'python',
'charset': 'utf8'
}
cnx = MySQLdb.connect(**db_config)
return cnx
if __name__ == '__main__':
cnx = connect_mysql()
#()中的sql语句是把所有学生名字重复的学生都列出来；此sql是关联查询
sql = '''select * from Student where StdName in (select StdName from Student group by StdName having count(1)>1 ) order by StdName;'''
try:
cus = cnx.cursor()
cus.execute(sql)
result = cus.fetchall()
with codecs.open('select.txt', 'w+') as f:
for line in result:
f.write(str(line))
f.write('\n')
cus.close()
cnx.commit()
except Exception as e:
cnx.rollback()
print('error')
raise e
finally:
cnx.close()