操作MYSQL

import pymysql

coon=pymysql.connect(
    host='118.XX.XX.40',user='XXX',passwd='123456',
    port=3306,db='XXX',charset='utf8'
)

cur=coon.cursor()#建立游标
#执行sql

######优化SQL
username='nhy'
pwd='123456'
# sql='select * from stu where username="%s"'%(username)
sql='select * from nhy where name="%s" and pwd="%s"'%(username,pwd)
print(sql)
cur.execute(sql)
res=cur.fetchall() #获取所有返回的结果 元组list
# print(res)
if  res:
    print('用户不存在')
else:
    print('用户已存在！')

cur.close()
coon.close()



数据库函数

def my_db(sql,port=3306,charset='utf8'):
    import pymysql
    host,user,passwd,db='118.XX.XX.XX','XXX','123456','XXX'
    coon=pymysql.connect(
        host=host,user=user,passwd=passwd,db=db,
        port=port,charset=charset
    )
    # 建立游标，指定cursor类型返回的是字典
    cur=coon.cursor(cursor=pymysql.cursors.DictCursor)
    cur.execute(sql)
    if sql.strip()[:6].upper()=='SELECT':
        # res=cur.fetchall()
        res = cur.fetchone()
        # cur.fetchmany()  #能传入一个数，返回多少条数据
    else:
        coon.commit()
        res='ok'
    cur.close()
    coon.close()
    return res

res=my_db('select * from stu limit 10; ')
print(res)


fetchall()
#获取到SQL执行的全部结果,它把数据库表里面的每一行数据放到一个LIST里面
# [['1','2','3']]  [{},{},{}]

fetchone()#获取到这个SQL执行的一条结果，它返回的就只是一条数据

如果sql语句执行的结果是多条数据时，那就用fetchall()
如果sql语句执行的结果是一条数据时，那就用fetchone()


def my_db(sql,port=3306,charset='utf8'):
    import pymysql
    host,user,passwd,db='118.XX.XX.XX','XXX','123456','XXX'
    coon=pymysql.connect(
        host=host,user=user,passwd=passwd,db=db,
        port=port,charset=charset
    )
    # 建立游标，指定cursor类型返回的是字典
    cur=coon.cursor(cursor=pymysql.cursors.DictCursor)
    cur.execute(sql)
    if sql.strip()[:6].upper()=='SELECT':
        print(cur.description)#获取字段的名字
        # print(cur.fetchone())
        # print(cur.fetchone())
        # print(cur.fetchone())
        res='xx'

    else:
        coon.commit()
        res='ok'
    cur.close()
    coon.close()
    return res

res=my_db('select * from stu limit 10; ')
print(res)







def my_db(sql,port=3306,charset='utf8'):
    import pymysql
    host,user,passwd,db='118.XX.XX.XX','XXX','123456','XXX'
    coon=pymysql.connect(
        host=host,user=user,passwd=passwd,db=db,
        port=port,charset=charset
    )
    # 建立游标，指定cursor类型返回的是字典
    cur=coon.cursor(cursor=pymysql.cursors.DictCursor)
    cur.execute(sql)
    if sql.strip()[:6].upper()=='SELECT':
        fileds=[]
        # for filed in cur.description:
        #     fileds.append(filed[0])

        # 和上面3行代码的意思是一样,cur.description动态获取到表的字段
        fileds=[fileds[0] for fileds in cur.description]
        print(fileds)
        res='xx'
    else:
        coon.commit()
        res='ok'
    cur.close()
    coon.close()
    return res

res=my_db('select * from stu limit 10; ')
print(res)