Flask 数据库连接
初级阶段
import pymysql
from flask import Flask
app = Flask(__name__)
def fetchall(sql):
conn = pymysql.connect(host='home.vimll.com', port=xxxxxx, user='python', passwd='xxxxxx', db='test')
cursor = conn.cursor()
cursor.execute(sql)
result = cursor.fetchall()
cursor.close()
conn.close()
return result
@app.route('/login')
def login():
result = fetchall('select * from employees')
return 'login'
@app.route('/index')
def index():
result = fetchall('select * from employees')
return 'xxx'
@app.route('/order')
def order():
result = fetchall('select * from `order`')
print(result)
return 'xxx'
if __name__ == '__main__':
app.run()
* Serving Flask app '__main__'
* Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
127.0.0.1 - - [14/May/2024 09:32:04] "GET /order HTTP/1.1" 200 -
((1, 'shkstart'), (2, 'tomcat'), (3, 'dubbo'))中级阶段
import pymysql
from flask import Flask
app = Flask(__name__)
CONN = pymysql.connect(host='home.vimll.com', port=xxxxxx, user='python', passwd='xxxxxx', db='test')
def fetchall(sql):
cursor = CONN.cursor()
cursor.execute(sql)
result = cursor.fetchall()
cursor.close()
return result
@app.route('/login')
def login():
result = fetchall('select * from user')
return 'login'
@app.route('/index')
def index():
result = fetchall('select * from user')
return 'xxx'
@app.route('/order')
def order():
result = fetchall('select * from user')
return 'xxx'
if __name__ == '__main__':
app.run()数据库连接池
- pip3 install dbutils
- pip3 install pymysql
import pymysql
# from DBUtils.PooledDB import PooledDB
from dbutils.pooled_db import PooledDB
POOL = PooledDB(
creator=pymysql, # 使用链接数据库的模块
maxconnections=500, # 连接池允许的最大连接数，0和None表示不限制连接数
mincached=5, # 初始化时，链接池中至少创建的链接，0表示不创建
blocking=True, # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
ping=0, # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
host='home.vimll.com',
port=xxxxxx,
user='python',
password='xxxxxx',
database='test',
charset='utf8'
)
# 去连接池中获取一个连接
conn = POOL.connection()
cursor = conn.cursor()
cursor.execute('select * from `order`')
result = cursor.fetchall()
cursor.close()
# 将连接放会到连接池
conn.close()
print(result)
((1, 'shkstart'), (2, 'tomcat'), (3, 'dubbo'))多线程连接测试
from threading import Thread
import pymysql
from dbutils.pooled_db import PooledDB
POOL = PooledDB(
creator=pymysql, # 使用链接数据库的模块
maxconnections=20, # 连接池允许的最大连接数，0和None表示不限制连接数
mincached=5, # 初始化时，链接池中至少创建的链接，0表示不创建
blocking=True, # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
ping=0, # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
host='home.vimll.com',
port=xxxxxx,
user='python',
password='xxxxxx',
database='test',
charset='utf8'
)
def task(num, sql):
# 去连接池中获取一个连接
conn = POOL.connection()
cursor = conn.cursor()
# cursor.execute('select * from `order`')
# cursor.execute('select sleep(3)')
cursor.execute(sql)
result = cursor.fetchall()
cursor.close()
conn.close() # 将连接放会到连接池
print(num, '------------>', result)
for i in range(50):
sql = 'select * from `order`;'
t = Thread(target=task, args=(i, sql))
t.start()基于函数实现sqlhelper
./sqlhelper.py
import pymysql
# from DBUtils.PooledDB import PooledDB
from dbutils.pooled_db import PooledDB
POOL = PooledDB(
creator=pymysql, # 使用链接数据库的模块
maxconnections=6, # 连接池允许的最大连接数，0和None表示不限制连接数
mincached=2, # 初始化时，链接池中至少创建的链接，0表示不创建
blocking=True, # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
ping=0, # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
host='home.vimll.com',
port=xxxxxx,
user='python',
password='xxxxxx',
database='test',
charset='utf8'
)
def fetchall(sql,*args):
""" 获取所有数据 """
conn = POOL.connection()
cursor = conn.cursor()
cursor.execute(sql,args)
result = cursor.fetchall()
cursor.close()
conn.close()
return result
def fetchone(sql, *args):
""" 获取单条数据 """
conn = POOL.connection()
cursor = conn.cursor()
cursor.execute(sql, args)
result = cursor.fetchone()
cursor.close()
conn.close()
return result
from flask import Flask
import sqlhelper
app = Flask(__name__)
@app.route('/login')
def login():
result = sqlhelper.fetchone('select * from `order` where order_id=%s;','1')
print(result)
return 'login'
@app.route('/index')
def index():
result = sqlhelper.fetchall('select * from `order`')
print(result)
return 'xxx'
@app.route('/order')
def order():
# result = fetchall('select * from user')
return 'xxx'
if __name__ == '__main__':
app.run()
基于类实现sqlhelper
./sqlhelper2.py
import pymysql
from dbutils.pooled_db import PooledDB
class SqlHelper(object):
def __init__(self):
self.pool = PooledDB(
creator=pymysql, # 使用链接数据库的模块
maxconnections=6, # 连接池允许的最大连接数，0和None表示不限制连接数
mincached=2, # 初始化时，链接池中至少创建的链接，0表示不创建
blocking=True, # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
ping=0,
# ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always
host='home.vimll.com',
port=xxxxxx,
user='python',
password='xxxxxx',
database='test',
charset='utf8'
)
def open(self):
"""创建连接"""
conn = self.pool.connection()
cursor = conn.cursor()
return conn, cursor
def close(self, cursor, conn):
"""关闭连接"""
cursor.close()
conn.close()
def fetchall(self, sql, *args):
""" 获取所有数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchall()
self.close(conn, cursor)
return result
def fetchone(self, sql, *args):
""" 获取一条数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchone()
self.close(conn, cursor)
return result
def fetchmany(self, sql, *args, num=1):
""" 获取指定多少条数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchmany(size=num)
self.close(conn, cursor)
return result
# 在这里生成一个对象，外表调用自然是单例模式
db = SqlHelper()
if __name__ == '__main__':
from sqlhelper2 import db
result = db.fetchone('select * from `order` where order_id=%s;', '1')
print(result)
result1 = db.fetchall('select * from `order`;')
print(result1)
result2 = db.fetchmany('select * from `order`;', num=2)
print(result2)from flask import Flask
from sqlhelper2 import db
app = Flask(__name__)
@app.route('/login')
def login():
result = db.fetchone('select * from `order` where order_id=%s;', '1')
print(result)
return 'login'
@app.route('/all')
def all():
result = db.fetchall('select * from `order`;')
print(result)
return 'xxx'
@app.route('/index')
def index():
result = db.fetchmany('select * from `order`;', num=2)
print(result)
return 'xxx'
@app.route('/order')
def order():
# db.fetchall()
conn, cursor = db.open()
# 自己做操作
cursor.execute('select * from `order` where order_id=%s;', '1')
result = cursor.fetchone()
print(result)
db.close(conn, cursor)
return 'xxx'
if __name__ == '__main__':
app.run()* Serving Flask app '__main__'
* Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
127.0.0.1 - - [14/May/2024 13:56:15] "GET /index HTTP/1.1" 200 -
((1, 'shkstart'), (2, 'tomcat'))上下文管理和sqlhelper
import pymysql
from dbutils.pooled_db import PooledDB
class SqlHelper(object):
def __init__(self):
self.pool = PooledDB(
creator=pymysql,
maxconnections=6,
mincached=2,
blocking=True,
ping=0,
host='home.vimll.com',
port=xxxxxx,
user='python',
password='xxxxxx',
database='test',
charset='utf8'
)
def open(self):
"""创建连接"""
conn = self.pool.connection()
cursor = conn.cursor()
return conn, cursor
def close(self, cursor, conn):
"""关闭连接"""
cursor.close()
conn.close()
def fetchall(self, sql, *args):
""" 获取所有数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchall()
self.close(conn, cursor)
return result
def fetchone(self, sql, *args):
""" 获取一条数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchone()
self.close(conn, cursor)
return result
def fetchmany(self, sql, *args, num=1):
""" 获取指定多少条数据 """
conn, cursor = self.open()
cursor.execute(sql, args)
result = cursor.fetchmany(size=num)
self.close(conn, cursor)
return result
db = SqlHelper()
if __name__ == '__main__':
from sqlhelper2 import db
result = db.fetchone('select * from `order` where order_id=%s;', '1')
print(result)
result1 = db.fetchall('select * from `order`;')
print(result1)
result2 = db.fetchmany('select * from `order`;', num=2)
print(result2)from flask import Flask
from sqlhelper3 import db
app = Flask(__name__)
@app.route('/login')
def login():
result = db.fetchone('select * from `order` where order_id=%s;', '1')
print(result)
return 'login'
@app.route('/all')
def all():
result = db.fetchall('select * from `order`;')
print(result)
return 'xxx'
@app.route('/index')
def index():
result = db.fetchmany('select * from `order`;', num=2)
print(result)
return 'xxx'
@app.route('/order')
def order():
# db.fetchall()
conn, cursor = db.open()
# 自己做操作
cursor.execute('select * from `order` where order_id=%s;', '1')
result = cursor.fetchone()
print(result)
db.close(conn, cursor)
return 'xxx'
@app.route('/test')
def test():
with db as cur:
cur.execute('select * from `order` where order_id=%s;', '1')
with db as cur2:
cur2.execute('select * from `order` where order_id=%s;', '2')
result = cur.fetchone()
result2 = cur2.fetchone()
return 'xxx'
if __name__ == '__main__':
app.run()* Serving Flask app '__main__'
* Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
127.0.0.1 - - [14/May/2024 14:18:38] "GET /all HTTP/1.1" 200 -
((1, 'shkstart'), (2, 'tomcat'), (3, 'dubbo'))
127.0.0.1 - - [14/May/2024 14:18:48] "GET /index HTTP/1.1" 200 -
((1, 'shkstart'), (2, 'tomcat'))
127.0.0.1 - - [14/May/2024 14:18:56] "GET /test HTTP/1.1" 200 -
(1, 'shkstart')
None None None