Pymysql module of Python - MySQL

Yongliang 2020-11-10 17:23:25
pymysql module python mysql


1、PyMySQL Installation

pymysql Is in Python3 Version for connecting mysql A library of servers ,Python2 Is used in mysqldb.

pip3 install PyMySQL

2、 Use python operation mysql database

(1)、python Connect mysql database

import pymysql
db = pymysql.connect(" database ip"," user "," password "," database ") # Open database connection
cursor = db.cursor() # Get an executable SQL Cursor object for statement
cursor.execute("SELECT VERSION()") # Use execute() Method execution SQL Inquire about
data = cursor.fetchone() # Use fetchone() Method to get a single piece of data
print ("Database version : %s " % data)
db.close() # Close database connection

(2)、 Create table operation

import pymysql
# Open database connection
db = pymysql.connect("localhost","testuser","test123","TESTDB" )
# Use cursor() Method to create a cursor object cursor
cursor = db.cursor()
# Use execute() Method execution SQL, Delete... If the table exists
cursor.execute("DROP TABLE IF EXISTS EMPLOYEE")
# Use preprocessing statements to create tables
sql = """CREATE TABLE EMPLOYEE (
FIRST_NAME CHAR(20) NOT NULL,
LAST_NAME CHAR(20),
AGE INT,
SEX CHAR(1),
INCOME FLOAT )"""
cursor.execute(sql)
# Close database connection
db.close()

(3)、 Add, delete, modify and check the data

import pymysql
# One 、 Open database connection
conn=pymysql.connect(host='localhost',user='testuser',password="test123",database='TESTDB')
# Two 、 To obtain the cursor
cur = conn.cursor(pymysql.cursors.DictCursor) # cur The cursor cur Database operators ( It's equivalent to the file operator -- File handle f)
# 3、 ... and 、 Add, delete, modify and search the data
# check
ret = cur.execute('select * from books') # Use execute() Method execution SQL Inquire about ; execute Put... In the method mysql Query statement ;ret Number of rows affected , Here is the number of data rows found
for i in range(ret): # ret Is the number of rows of data
row1 = cur.fetchone() # Take one piece of data at a time
print(row1)
row2 = cur.fetchmany(3) # According to the specified parameters n strip
print(row2)
row3 = cur.fetchall() # Take all , It's a waste of memory
print(row3)
# increase Change Delete Submit ( The addition, deletion and modification are similar to , Use corresponding mysql Sentence can be used )
# insert update delete conn.commit()
cur = conn.cursor() # cur The cursor cur Database operators
cur.execute('insert into books values(" learn python From beginning to giving up ","cai"," Home squatting University Press ",50,"2019-6-1")') # stay execute Methods add, delete and modify related mysql sentence
conn.commit() # Submit , Commit to database execution

(4)、 Operation file

## file file The contents of the document
'''
learn python From beginning to giving up |cai| Home squatting University Press |50|2018-7-1
learn mysql From beginning to giving up |ling| Urban and rural industry press |60|2018-6-3
learn html From beginning to giving up |liu| Urban and rural industry press |20|2018-4-1
learn css From beginning to giving up |liangliang| Urban and rural industry press |120|2018-5-2
learn js From beginning to giving up |yongliang| Urban and rural industry press |100|2018-7-30
'''
import pymysql
conn=pymysql.connect(host='localhost',user='testuser',password="test123",database='TESTDB')
cur = conn.cursor()
sql = 'insert into books values(%s,%s,%s,%s,%s)'
with open('file',encoding='utf-8') as f:
for line in f:
try:
lst = line.strip().split('|')
cur.execute(sql,lst) # execute('insert into books values(%s,%s,%s,%s,%s)'[" learn python From beginning to giving up ","cai"," Home squatting University Press ",50,"2018-7-1")'])
conn.commit()
except:
conn.rollback() # Roll back if an error occurs
cur.close() # Close cursor
conn.close() # Close the connection

3、SQL Inject

# Log in to register + database surface userinfo
import pymysql
conn=pymysql.connect(host='localhost',user='testuser',password="test123",database='TESTDB')
cur = conn.cursor()
name = input('user:')
passwd = input('password:')
sql = "select * from userinfo where username = %s and password = %s;"
print(sql)
ret = cur.execute(sql,(name,passwd))
if ret: # ret = 1
print(' Landing successful ')
else: # ret = 0
print(' Login failed ')
# sql Injection problem
select * from userinfo where username = 'xxx' or 1=1 ; # -- ' and password =

Summary :

1. Establishing a connection conn
2. To obtain the cursor cur
3. perform sql execute(sql , ( Parameter sets of iteratable types ))
sql It's cha --- It only involves the reading of files
fetchone()
fetchmany(n)
fetchall()
Additions and deletions --- It's about writing files
conn.commit()
4. Close cursors and connections
cur.close()
conn.close()
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本文为[Yongliang]所创,转载请带上原文链接,感谢

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