Python: 03. python-pymysql 连接mysql 数据库

查询实例

1. 安装pymysql 依赖

C:\Users\wu-chao>pip install pymysql
Collecting pymysql
  Downloading PyMySQL-0.8.0-py2.py3-none-any.whl (83kB)
    100% |████████████████████████████████| 92kB 150kB/s
Installing collected packages: pymysql
Successfully installed pymysql-0.8.0

C:\Users\wu-chao>

02 代码导入pymysql

# coding:utf-8

import pymysql.cursors;

03 连接mysql

connection=pymysql.connect(host="localhost",port=3306,user="root",password="root",db="test");

04 打开游标

# 通过cursor创建默认游标
cursor = connection.cursor();

# pymysql.cursor 默认返回的数据行是元祖类型，若要返回key-map，需在打开游标的时候设置数据行的数据类型为字典类型：
# 游标设置为字典类型
cursor = connection.cursor(cursor=pymysql.cursors.DictCursor);

05 游标执行sql 语句

# sql字符串拼接查询
sql="select empno,ename,job from emp";

# 返回数据行数
count=cursor.execute(sql);

05(2) 参数化查询

sql="select empno,ename,job,deptno from emp where deptno=%s and job=%s";
count=cursor.execute(sql,("20","ANALYST"));

06(1) 提取数据：for 循环

print "一共提取到%d条数据"%count
datas=cursor.fetchall(); #得到一个二维元祖
for row in datas:
    print row #得到元祖
 一共提取到14条数据
(7369, 'SMITH', 'CLERK')
……
(7902, 'FORD', 'ANALYST')
(7934, 'MILLER', 'CLERK')   

06(2) 提取数据：while 逐行（fetchone）提取：方法一

while True:
    row=cursor.fetchone();
    if row is None:
        break
    print(row)
 一共提取到14条数据
(7369, 'SMITH', 'CLERK')
……
(7902, 'FORD', 'ANALYST')
(7934, 'MILLER', 'CLERK') 

06(3) 提取数据：while 逐行（fetchone）提取：方法二

row=cursor.fetchone();
while row is not None:
    if row!= None: print row;
    row=cursor.fetchone();

8. 关闭资源：cursor connection

cursor.close();
connection.close();

完整代码

# coding:utf-8

import pymysql.cursors;

connection=pymysql.connect(host="localhost",port=3306,user="root",password="root",db="test");

# 通过cursor创建默认游标
cursor = connection.cursor();

# pymysql.cursor 默认返回的数据行是元祖类型，若要返回key-map，需在打开游标的时候设置数据行的数据类型为字典类型：
# 游标设置为字典类型
cursor = connection.cursor(cursor=pymysql.cursors.DictCursor);

# 游标设置为字典类型
cursor = connection.cursor(cursor=pymysql.cursors.DictCursor)

sql="select empno,ename,job,deptno from emp where deptno=%s and job=%s";
count=cursor.execute(sql,("20","ANALYST"));

print "一共提取到%d条数据"%count

# 提取数据：for 循环
# datas=cursor.fetchall();
# for row in datas:
#     print row

# 提取数据：while 逐行（fetchone）提取：方法一
# while True:
#     row=cursor.fetchone();
#     if row is None:
#         break
#     print(row)

# 提取数据：while 逐行（fetchone）提取：方法二
row=cursor.fetchone();
while row is not None:
    if row!= None: print row;
    row=cursor.fetchone();

# 关闭资源：cursor connection
cursor.close();
connection.close();