前言
昨天,因为项目需求要添加表的更新接口,来存储预测模型训练的数据,所以自己写了一段代码实现了该功能,在开始之前,给大家分享python 操作mysql数据库基础:
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#coding=utf-8
import MySQLdb
conn = MySQLdb.connect(
host = 'localhost' ,
port = 3306 ,
user = 'root' ,
passwd = '123456' ,
db = 'test' ,
)
cur = conn.cursor()
#创建数据表
#cur.execute("create table student(id int ,name varchar(20),class varchar(30),age varchar(10))")
#插入一条数据
#cur.execute("insert into student values('2','Tom','3 year 2 class','9')")
#修改查询条件的数据
#cur.execute("update student set class='3 year 1 class' where name = 'Tom'")
#删除查询条件的数据
#cur.execute("delete from student where age='9'")
cur.close()
conn.commit()
conn.close()
|
>>> conn = MySQLdb.connect(host='localhost',port = 3306,user='root', passwd='123456',db ='test',)
Connect() 方法用于创建数据库的连接,里面可以指定参数:用户名,密码,主机等信息。
这只是连接到了数据库,要想操作数据库需要创建游标。
>>> cur = conn.cursor()
通过获取到的数据库连接conn下的cursor()方法来创建游标。
>>> cur.execute("create table student(id int ,name varchar(20),class varchar(30),age varchar(10))")
通过游标cur 操作execute()方法可以写入纯sql语句。通过execute()方法中写如sql语句来对数据进行操作。
>>>cur.close()
cur.close() 关闭游标
>>>conn.commit()
conn.commit()方法在提交事物,在向数据库插入一条数据时必须要有这个方法,否则数据不会被真正的插入。
>>>conn.close()
Conn.close()关闭数据库连接
下面开始本文的正文:
Python实现mysql更新表数据接口
示例代码
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# -*- coding: utf-8 -*-
import pymysql
import settings
class mysql( object ):
def __init__( self ):
self .db = None
def connect( self ):
self .db = pymysql.connect(host = settings.ip, port = settings.port, user = settings.mysql_user, passwd = settings.mysql_passwd, db = settings.database, )
# print("connect is ok")
# return 1
def disconnect( self ):
self .db.close()
# return -1
def create_table( self , tablename, columns, spec = 'time' ):
"""
:param tablename:
:param spec:
:param columns: 列表[]
:return:
"""
type_data = [ 'int' , 'double(10,3)' ]
cursor = self .db.cursor()
sql = "create table %s(" % (tablename,)
sqls = []
for col in columns:
#判断是否time_num
if col = = spec:
sqls.append( '%s %s primary key' % (col,type_data[ 0 ]))
else :
sqls.append( '%s %s' % (col,type_data[ 1 ]))
sqlStr = ',' .join(sqls)
sql + = sqlStr + ')'
try :
cursor.execute(sql)
print ( "Table %s is created" % tablename)
except :
self .db.rollback()
def is_table_exist( self , tablename,dbname):
cursor = self .db.cursor()
sql = "select table_name from information_schema.TABLES where table_schema='%s' and table_name = '%s'" % (dbname,tablename)
#results="error:Thie table is not exit"
try :
cursor.execute(sql)
results = cursor.fetchall() #接受全部返回行
except :
#不存在这张表返回错误提示
raise Exception( 'This table does not exist' )
if not results:
return None
else :
return results
# print datas
def insert_mysql_with_json( self , tablename, datas):
"""
:param tablename:
:param datas:字典{(key: value),.....}
:return:
"""
# keys = datas[0]
keys = datas[ 0 ].keys()
keys = str ( tuple (keys))
keys = ' '.join(keys.split("' ")) # 用' 隔开
print (keys)
ret = []
for dt in datas:
values = dt.values() ## ‘str' object has no attribute#
sql = "insert into %s" % tablename + keys
sql = sql + " values" + str ( tuple (values))
ret.append(sql)
# print("1")
# print keys insert into %tablename dat[i] values str[i]
self .insert_into_sql(ret)
print ( "1" )
def insert_into_sql( self ,sqls):
cursor = self .db.cursor()
for sql in sqls:
# 执行sql语句
try :
cursor.execute(sql)
self .db.commit()
# print("insert %s" % sql, "success.")
except :
# Rollback in case there is any error
self .db.rollback()
#找列名
def find_columns( self , tablename):
sql = "select COLUMN_NAME from information_schema.columns where table_name='%s'" % tablename
cursor = self .db.cursor()
try :
cursor.execute(sql)
results = cursor.fetchall()
except :
raise Exception( 'hello' )
return tuple ( map ( lambda x: x[ 0 ], results))
def find( self , tablename, start_time, end_time, fieldName = None ):
"""
:param tablename: test_scale1015
:param fieldName: None or (columns1010, columns1011, columns1012, columns1013, time)
:return:
"""
cursor = self .db.cursor()
sql = ''
if fieldName = = None :
fieldName = self .find_columns(tablename)
sql = "select * from %s where time between %s and %s" % (tablename, str (start_time), str (end_time))
# print('None')
else :
fieldNameStr = ',' .join(fieldName)
sql = "select %s from %s where time between %s and %s" % (
fieldNameStr, tablename, str (start_time), str (end_time))
# print('sm')
try :
cursor.execute(sql)
results = cursor.fetchall()
except :
raise Exception( 'hello' )
return fieldName, results,
#样例 data = [{'time':123321,'predict':1.222},{'time':123322,'predict':1.223},{'time':123324,'predict':1.213}]
def updata( self ,datas, tablename):
cursor = self .db.cursor()
columns = []
for data in datas:
for i in data.keys():
columns.append(i)
# print(columns)
break
# columns_2=columns[:]
db.connect()
if db.is_table_exist(settings.tablename_2, settings.database):
# exists
# pass
for col in columns:
if col ! = 'time' :
sql = "alter table %s add column %s double(10,3);" % (settings.tablename_2, col)
try :
cursor.execute(sql)
print ( "%s is altered ok" % (col))
except :
print ( "alter is failed" )
ret = []
for i in datas:
col = []
for ii in i.keys():
col.append(ii)
#time = col[0] and predict = col[1]
time_data = i[col[ 0 ]]
predic_data = i[col[ 1 ]]
sql = "update %s set %s='%s'where %s=%s" % (settings.tablename_2,col[ 1 ],predic_data,col[ 0 ],time_data)
ret.append(sql)
self .insert_into_sql(ret)
# db.insert_mysql_with_json(tablename, datas)
else :
# no exists
db.create_table(settings.tablename_2, columns)
db.insert_mysql_with_json(settings.tablename_2, datas)
db = mysql()
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其中update()函数,是新添加的接口:
传入的data的样例 data = [{'time':123321,'predict':1.222},{'time':123322,'predict':1.223},{'time':123324,'predict':1.213}]
这样子的。
一个列表里有多个字典,每个字典有time和predict。如果需要存predict_2,predict_3的时候,则实现更新操作,否则,只进行创表和插入数据的操作~~~~~~
看起来是不是很简单~~~~~~
这个接口还没有进行优化等操作,很冗余~~~~
毕竟项目还在测试阶段,等先跑通了,在考虑优化吧~~~~~~
总结
以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作具有一定的参考学习价值,如果有疑问大家可以留言交流,谢谢大家对服务器之家的支持。
原文链接:http://www.cnblogs.com/BigStupid/p/7859429.html