pymysql library - python operation mysql

Environment: Win10 x64 + Python 3.7 + PyMySQL 1.0.2 + MySQL 8.0.27

1 installation

pip install pymysql

2 addresses

https://pypi.org/project/pymysql/

3.1 Database version query (search_version.py)

import pymysql

# 打开数据库连接
try:
    db = pymysql.connect(host='localhost', user='root', passwd='123456', port=3306)
    print('连接成功！')
except:
    print('something wrong!')

# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()

# 使用 execute()  方法执行 SQL 查询
cursor.execute("SELECT VERSION()")

# 使用 fetchone() 方法获取单条数据.fetchone只返回一维元组
data = cursor.fetchone()
print(type(data))
print(data)
print("Database version : %s " % data)

# 关闭数据库连接
db.close()

'''
连接成功！
<class 'tuple'>
('8.0.27',)
Database version : 8.0.27 
'''

3.2 Create table (create_table.py)

import pymysql

# 打开数据库连接
try:
    db = pymysql.connect(host='localhost', user='root', passwd='123456', port=3306, db='db_jupiter')
    print('连接成功！')
except:
    print('something wrong!')

# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()

# 使用 execute() 方法执行 SQL，如果表存在则删除
cursor.execute("DROP TABLE IF EXISTS EMPLOYEE")

# 使用预处理语句创建表
sql = """CREATE TABLE EMPLOYEE (
        ID INT NOT NULL AUTO_INCREMENT,
         FIRST_NAME  CHAR(20) NOT NULL COMMENT '名字',
         LAST_NAME  CHAR(20),
         AGE INT COMMENT '年龄',  
         SEX CHAR(1) COMMENT '性别',
         INCOME FLOAT NOT NULL COMMENT '收入',
         PRIMARY KEY (ID)
         )"""

cursor.execute(sql)
print('建表成功！')

# 关闭数据库连接
db.close()

'''
连接成功！
建表成功！
'''

3.3 Insert data (insert_update_delete_table.py)

import pymysql

# 打开数据库连接
try:
    db = pymysql.connect(host='localhost', user='root', passwd='123456', port=3306, db='db_jupiter')
    print('连接成功！')
except:
    print('something wrong!')

# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()

# SQL 插入语句
# sql = """INSERT INTO EMPLOYEE(FIRST_NAME,LAST_NAME, AGE, SEX, INCOME) VALUES ('Qin', 'DeXu', 20, 'M', 2000)"""
# sql = """INSERT INTO EMPLOYEE(FIRST_NAME,LAST_NAME, AGE, SEX, INCOME) VALUES ('Li', 'Xiaofei', 20, 'F', 3000)"""
sql = """INSERT INTO EMPLOYEE(FIRST_NAME,LAST_NAME, AGE, SEX, INCOME) VALUES ('Wang', 'HanYu', 20, 'M', 5000)"""

# SQL 更新语句
# sql = "UPDATE EMPLOYEE SET AGE = AGE + 1 WHERE SEX = '%c'" % ('M')

# SQL 删除语句
# sql = "DELETE FROM EMPLOYEE WHERE AGE > %d" % (20)

try:
    # 执行sql语句
    cursor.execute(sql)
    # 提交到数据库执行
    db.commit()
    print('数据插入成功！')
except:
    # 如果发生错误则回滚
    db.rollback()
    print('数据插入错误！')

# 关闭数据库连接
db.close()

'''
连接成功！
数据插入成功！
'''

3.4 Insert data in batches (insert_table_many.py)

import pymysql

# 打开数据库连接
try:
    db = pymysql.connect(host='localhost', user='root', passwd='123456', port=3306, db='db_jupiter')
    print('连接成功！')
except:
    print('something wrong!')

# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()

# SQL 插入语句
data = [
  ('DongFang', 'YuXiao', 25, 'M', 2000.30),
  ('OuYang', 'HeHe', 22, 'F', 2000),
  ('GongSun', 'Sheng', 23, 'M', 2000)
]

stmt = "INSERT INTO EMPLOYEE (FIRST_NAME,LAST_NAME, AGE, SEX, INCOME) VALUES (%s, %s, %s, %s, %s)"

try:
    # 执行sql语句
    cursor.executemany(stmt, data)
    # 提交到数据库执行
    db.commit()
    print('数据插入成功！')
except:
    # 如果发生错误则回滚
    db.rollback()
    print('数据插入错误！')

# 关闭数据库连接
db.close()

'''
连接成功！
数据插入成功！
'''

'''
说明：
占位符 %s 改成 %d ，报错。
'''

3.5 Query data (search_table.py)

import pymysql

# 打开数据库连接
try:
    db = pymysql.connect(host='localhost', user='root', passwd='123456', port=3306, db='db_jupiter')
    print('连接成功！')
except:
    print('something wrong!')

# 使用 cursor() 方法创建一个游标对象 cursor
cursor = db.cursor()

# SQL 查询语句
sql = "SELECT * FROM EMPLOYEE WHERE INCOME >= %s" % (3000)

try:
    # 执行SQL语句
    cursor.execute(sql)

    # rowcount: 这是一个只读属性，并返回执行execute()方法后影响的行数。
    row_count = cursor.rowcount
    print(type(row_count))
    print(row_count)

    # fetchall(): 接收全部的返回结果行, 获取所有记录列表 fetchall返回二维元组（元组中含有元组)
    results = cursor.fetchall()
    print(type(results))
    print(results)

    for row in results:
        id = row[0]
        fname = row[1]
        lname = row[2]
        age = row[3]
        sex = row[4]
        income = row[5]
        # 打印结果
        print('数据查询成功！')
        print("id=%s, fname=%s, lname=%s, age=%s, sex=%s, income=%s" % (id, fname, lname, age, sex, income))
except:
    print("Error: unable to fetch data")

# 关闭数据库连接
db.close()

'''
连接成功！
<class 'int'>
2
<class 'tuple'>
((2, 'Li', 'Xiaofei', 20, 'F', 3000.0), (3, 'Wang', 'HanYu', 20, 'M', 5000.0))
数据查询成功！
id=2, fname=Li, lname=Xiaofei, age=20, sex=F, income=3000.0
数据查询成功！
id=3, fname=Wang, lname=HanYu, age=20, sex=M, income=5000.0
'''

Other situations:
The executemany() method requires that the parameter passed in is a nested list of tuples. Each tuple in the list represents a set of data, and each value in the tuple represents a field value of the data.

####################################
Batch insert 1:
data = [
  ('Jane', date( 2005, 2, 12)),
  ('Joe', date(2006, 5, 23)),
  ('John', date(2010, 10, 3)),
]

stmt = "INSERT INTO employees (first_name, hire_date) VALUES (%s, %s)"
cursor.executemany(stmt, data)

INSERT INTO employees (first_name, hire_date)
VALUES ('Jane', '2005-02-12'), ('Joe', '2006-05-23'), ('John', '2010-10-03')

###################################
Batch Insert 2:
# Define SQL statement
insert_sql = "INSERT INTO person VALUES (%s, %s, %s)"

# Define data
data = [
    ('1', 'Zhang San', 18),
    ('2', '李思', 19),
    ('3', '王五', 20)
]
# Batch insert data
cursor .executemany(insert_sql, data)

Batch deletion 3:
# Define SQL statement
delete_sql = "DELETE FROM WHERE id = %s"
# Define data
ids = [(1,), (2,), (3,)]
# Batch delete data
cursor.executemany(delete_sql, ids)

Reference links:
https://zhuanlan.zhihu.com/p/397765212
http://www.xoxxoo.com/index/index/article/id/288
https://blog.csdn.net/m0_48300767/article/details /131063781
https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-executemany.html