python - MySQL 取出数据很慢

Question

我需要将 MySQL 工作台中的一些数据导入 Python，以便制作图表。但是当我尝试插入它并尝试打印值时，这是使用 pymysql (参见代码)。运行速度非常慢。

所以我认为当我做实时图表和更多东西时程序会卡住......

有人有解决办法吗？

我的代码:

import pymysql

conn= pymysql.connect(host='127.0.0.1',
                      port= 3306,
                      user= 'root',
                      passwd= '******',
                      db= 'energie'
                      )
a = conn.cursor()

sql1 = 'SELECT `VarValue`, `VarName` from `gasmeter1`;'
a.execute(sql1)

gasmeter1 = a.fetchone()

sql2 = 'SELECT `VarValue` from `gasmeter2`;'
a.execute(sql2)

gasmeter2 = a.fetchone()

sql3 = 'SELECT `VarValue` from `gasmeter349`;'
a.execute(sql3)

gasmeter349 = a.fetchone()

sql4 = 'SELECT `VarValue` from `binnentemp ahu3010`;'
a.execute(sql4)

Binnentemperatuur = a.fetchone()

sql5 = 'SELECT `VarValue` from `buiten temp241`;'
a.execute(sql5)

Buitentemperatuur = a.fetchone()

print (gasmeter1[0] , gasmeter2[0] , gasmeter349[0] , Buitentemperatuur[0] , Binnentemperatuur[0])

这只是一个简单的代码，但是速度很慢。有人建议吗？

时间:

代码:

import pymysql
import time

conn= pymysql.connect(host='127.0.0.1',
                    port= 3306,
                    user= 'root',
                    passwd= 'ohdecg',
                    db= 'energie'
                     )

a = conn.cursor()

t1 = time.time()

sql1 = 'SELECT `VarValue` from `gasmeter1`;'
a.execute(sql1)

gasmeter1 = a.fetchone ()

sql2 = 'SELECT `VarValue` from `gasmeter2`;'
a.execute(sql2)

gasmeter2 = a.fetchone ()

sql3 = 'SELECT `VarValue` from `gasmeter349`;'
a.execute(sql3)

gasmeter349 = a.fetchone ()

sql4 = 'SELECT `VarValue` from `binnentemp ahu3010`;'
a.execute(sql4)

Binnentemperatuur = a.fetchone()

sql5 = 'SELECT `VarValue` from `buiten temp241`;'
a.execute(sql5)

Buitentemperatuur = a.fetchone()

t2 = time.time()
print("The SQL statement took : {} s".format(t2 - t1))
#print (gasmeter1[0] , gasmeter2[0], gasmeter349[0])

>>> 
========================= RESTART: C:\Python27\j.py =========================
The SQL statement took : 32.0269999504 s
>>> 

Answer 1

你们的 table 有多大？您每次都会检索整个表，然后只获取第一个元素。你可以尝试用这样的东西来计时:

import time
...

t1 = time.time()
sql4 = 'SELECT `VarValue` from `binnentemp ahu3010`;'
a.execute(sql4)
t2 = time.time()
print("The SQL statement took : {} s".format(t2 - t1))