SSH连接服务器PG数据库并提取数据

利用SSH连接服务器并从服务器上的PG数据库提取数据，保存为excel文件。

Python代码如下：

## connectted to postgresql DB in the local PC
import psycopg2
import paramiko
from sshtunnel import SSHTunnelForwarder
import xlsxwriter


#获取密钥
private_key=paramiko.RSAKey.from_private_key_file('privacy_key_filepath\\id_rsa')

with SSHTunnelForwarder(
        ssh_address_or_host=('192.168.2.9',22), #ssh主机IP+端口,本例局域网
        ssh_pkey=private_key,
        ssh_username='hrm',        
        remote_bind_address=('127.0.0.1',5432)) as server:  #数据库服务器地址及端口
#    server.start() #start ssh sever
    conn=psycopg2.connect(database="test_db",
                          user="tester",
                          password="test_user",
                          host="127.0.0.1",
                          port=server.local_bind_port) 
    print('connected to the DB successfully')    
    cur=conn.cursor()
    L=['title','content','url','user_name'] #列标题
    with xlsxwriter.Workbook('.\\train\\positive.xlsx') as wb1:  #事先需建立好train文件夹
        sheet=wb1.add_worksheet() #创建工作表对象
        bold=wb1.add_format({'bold':True}) #定义加粗的格式对象    
        for l in range(len(L)):
            sheet.write(0,l,L[l],bold) #将列标题插入表格 
        
        SQL1 = "SELECT title,content,url,user_name \
        FROM public.raw_data WHERE sentiment=1 AND created_at < '2018-07-06 12:00:00'"
    
        cur.execute(SQL1)
        numrows=int(cur.rowcount)
        rows=cur.fetchall() #返回全部的查询结果
        for i in range(numrows):
                g=rows[i]
                sheet.write(i+1,0,g[0])
                sheet.write(i+1,1,g[1])
                sheet.write(i+1,2,g[2])
                sheet.write(i+1,3,g[3])
                #sheet.write(i+1,4,g[4])