Encapsulate the general connection and query of the project with pymysql

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Preface

A project usually needs a database , And for python This language , Except that some frames come with orm Or extended orm( image django Bring their own orm,flask You need to expand orm), Use orm There must be his advantage , But there is no doubt that you need to spend time learning this orm, Next, Daniel will take you to use pymysql Simply sub assemble a universal connection , Close and query ！

pymysql Introduction and installation

PyMySQL Is in Python3.x Version for connecting MySQL A library of servers ,Python2 Use... In mysqldb.

Install at the terminal using the following instructions ：

pip3 install PyMySQL

pymysql Use

import  pymysql

#  Open database connection ,password Password for your database ,db It's the database name 
db = pymysql.connect(host="127.0.0.1",
                     user="root",
                     password=" ",
                     db=" ",
                     charset="utf8")

#  Use  cursor()  Method to create a cursor object 
cursor = db.cursor()

#  Use  execute()  Method execution  SQL  Inquire about  
cursor.execute("SELECT VERSION()")

#  Use  fetchone()  Method to get a single piece of data .
data = cursor.fetchone()

print("Database version : %s " % data)

# Close database connection 
db.close()

password Password for your database ,db It's the database name , Please set up your mysql database .

Pictured , I connected successfully and got the version of my database ！

Method execute Carry out our sql sentence .
When getting the result of execution , You can specify the number of results obtained , The following options are available ：

fetchone()         #  Get a piece of data of the search results 

fetchmany(n)       #  Get search results n Data 

fetchall()         #  Get all the data of the search results 

It should be noted that , Similar to the pointer when reading a file , If in the same code , First use fetchone() Get the first data of the search result , And then use fetchmany(2) Words , The pointer will read the execution result backwards at the current position of the search result , Instead of re reading the retrieved results from the beginning .
The result obtained is tuple ., Here's the picture ：

Encapsulate the general connection and query of the project

Please write the password and database by yourself

import pymysql

#  Create connection 
#return:  Connect , The cursor 
def get_conn():

    #  Create connection 
    conn = pymysql.connect(host="127.0.0.1",
                           user="root",
                           password="",
                           db="",
                           charset="utf8")
    #  Create cursors 
    cursor = conn.cursor()#  The result set returned after execution is displayed in tuples by default 
    return conn, cursor


#  Close cursor , Connect 
def close_conn(conn, cursor):
    cursor.close()
    conn.close()


def query(sql,*args):
    """  Encapsulate generic queries  :param sql: :param args: :return:  Return the query result ,((),(),) In the form of  """
    conn, cursor = get_conn()
    cursor.execute(sql,args)
    res = cursor.fetchall()
    close_conn(conn, cursor)
    return res

therefore , We only need to call query() Function is OK ,*args You can let it pass in any parameter or no parameter , It only needs sql The number of placeholders in the statement corresponds to the number of parameters ！

Use as shown in the figure below

Conclusion

As long as yours. sql Pass through ,pymsql It can also help you complete the project ！ It is not necessary to use orm Oh ！

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