Python-pymysql操作MySQL数据库

一、安装pymysql

py -m pip install pymysql;

二、pymysql数据库操作

1．简单示例

#coding=utf-8
import pymysql
## 打开数据库连接
conn = pymysql.connect(
    host = "127.0.0.1",
    port = 3306,
    user = "lgb",
    passwd = "Lgb@1234",
    db = "test",
    charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
print(cursor)
print(type(cursor))

2．创建数据库

#coding=utf-8
import pymysql
try:
    conn = pymysql.connect(
    host = "127.0.0.1",
    port = 3306,
    user = "lgb",
    passwd = "Lgb@1234"
    )
    cur = conn.cursor()
    cur.execute("CREATE DATABASE IF NOT EXISTS grdb DEFAULT CHARSET utf8 COLLATE utf8_general_ci;")
    cur.close()
    conn.close()
    print("创建数据库pythonDB成功! ")
except pymysql.Error as e:
    print("Mysql Error %d: %s" %(e.args[0],e.args[1]))

#COLLATE utf8_general_ci：大小写不敏感

3．创建表

#coding=utf-8
import pymysql
try:
    conn = pymysql.connect(
    host = "127.0.0.1",
    port = 3306,
    user = "lgb",
    passwd = "Lgb@1234")

    conn.select_db('grdb')  ## 选择pythonDB数据库
    cur = conn.cursor()     ## 获取游标
    ## 如果所建表已存在，删除重建
    cur.execute("drop table if exists User;")
    ## 执行建表sql语句
    cur.execute('''CREATE TABLE User (id int(11) DEFAULT NULL,name varchar(255) DEFAULT NULL,password varchar(255) DEFAULT NULL,birthday date DEFAULT NULL)ENGINE=innodb DEFAULT CHARSET=utf8;''')
    cur.close()
    conn.close()
    print(u"创建数据表成功")
except pymysql.Error as e:
    print("Mysql Error %d: %s" %(e.args[0],e.args[1]))

4．插入表数据

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
## 方式一：直接执行insert语句，插入一条数据
insert = cursor.execute("insert into user values(1,'Tom','123','1990-01-01')")
print(u"添加语句受影响的行数：",insert)
## 方式二：通过格式字符串传入值，此方式可以防止SQL注入
sql = "insert into user values(%s,%s,%s,%s)"
insert = cursor.execute(sql,(3,'lucy','efg','1993-02-01'))
print(u"添加语句受影响的行数：",insert)
## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print(u"sql语句执行成功！")

5．查询表数据语句

（1）逐条获取fetchone()

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
cursor.execute("select * from user")
while 1:
    res = cursor.fetchone()
    if res is None:
    ## 表示已经取完结果集
        break
    print(res)
    ## 将读取到的时间格式化
    print(res[-1].strftime("%Y-%m-%d"))
## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print("sql语句执行成功！")

#cursor.fetchone  一条一条获取数据,每条数据是元组

（2）获取n条数据fetchmany(n)

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
cursor.execute("select * from user")
## 获取游标处两条数据
resTuple = cursor.fetchmany(2)
print("结果集类型：",type(resTuple))
for i in resTuple:
    print(i)
## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print("sql语句执行成功！")

#cursor.fetchmany  获取前两行数据，每条数据是元组

（3）获取所有数据fetchall()

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
cursor.execute("select * from user")
## 获取所有的数据
resTuple = cursor.fetchall()
print("结果集类型：",type(resTuple))
for i in resTuple:
    print(i)
## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print("sql语句执行成功！")

#cursor.fetchall  获取数据,每条数据是元组

6．更新数据

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
## 查询一条数据
query = cursor.execute("select * from user")
print("表中所有数据：")
for i in cursor.fetchall():
  print(i)
## 批量更新数据
cursor.executemany("update user set password = %s where name=%s",[('tomx2x', 'tom'), ('amy2x', 'amy')])
## 查看更新后的结果
query = cursor.execute("select * from user")
print("表中所有数据：")
for i in cursor.fetchall():
  print(i)
## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print("sql语句执行成功！")

7．删除数据

#coding=utf-8
import pymysql
conn = pymysql.connect(
host = "127.0.0.1",
port = 3306,
user = "lgb",
passwd = "Lgb@1234",
db = "grdb",
charset = "utf8")
## 使用cursor()方法获取数据库的操作游标
cursor = conn.cursor()
cursor.execute("select * from user")
print("表中所有数据：")
for i in cursor.fetchall():
    print(i)
## 删除数据
delete = cursor.execute("delete from user where name='tom'")
print("删除语句影响的行数：",delete)
print("删除一条数据后，表中数据：")
cursor.execute("select * from user")
for i in cursor.fetchall():
    print(i)

## 关闭游标
cursor.close()
## 提交事务
conn.commit()
## 关闭数据库连接
conn.close()
print("sql语句执行成功！")