python连接各种数据库的类方法

连接postgresql数据库

import psycopg2
# 用来操作数据库的类
class GPCommand(object):
    # 类的初始化
    def __init__(self):
      self.hostname = '10.1.2.xx'
      self.username = 'xxx'
      self.password = 'xxx'
      self.database = 'xxx'
    def connectGp(self):
      try:
        #链接数据库
        #读取配置利用connect链接数据库
        self.connect = psycopg2.connect( host=self.hostname, user=self.username, password=self.password, dbname=self.database )
        #创建一个新的cursor
        self.cursor = self.connect.cursor()
        print("connect gp successful."+'\n' + '数据库连接成功')
        return ('con_successful')
      except psycopg2.Error:
          error = 'Failed to setup Postgres environment.\n{0}'.format(sys.exc_info())
          print('connect gp error.'+'\n' + '数据库连接失败')
          return 'con_error'+ error

    def insertTrans(self,trans_name,url_name):
      	pass

连接mysql数据库

import pymysql
    class MysqlDB:
        def __init__(self):
            self.hostname = '1x.1.2.xx'
            self.port = 3306
            self.username = 'xx'
            self.password = 'xx'
            self.database = 'xxxx'
        def connectmysql(self):
            try:
                condb = pymysql.connect(host=self.hostname, port=self.port, user=self.username, passwd=self.password, db=self.database)
                print("链接成功")
                return  condb
            except Exception as e:
                print("连接异常", e)
            # except Exception:
            #     info = sys.exc_info()
            #     print("连接异常", info[1])
     
        def insertTable(self):
        # 获取数据库连接
        condb = self.connectmysql()
        # 使用cursor() 方法创建一个游标对象 cursor
        cursor = condb.cursor()
        try:
            # 执行sql语句
            sql = "select * from cn_customer.bank"
            cursor.execute(sql)
            # 提交到数据库执行
            condb.commit()
        except Exception:  # 方法一：捕获所有异常
            # 如果发生异常，则回滚
            info = sys.exc_info()
            print("发生异常", info[1])
            condb.rollback()
        finally:
            # 最终关闭数据库连接
            condb.close()

连接sqlserver

import pymssql 

class SqlserverDB:
    def __init__(self):
        self.hostname = 'xxx.1.2.xxxx'
        self.username = 'xxxxxx'
        self.password = 'xxxxx'
        self.database = 'xxxxx'
    def connectmysql(self):
        try:
            condb = pymssql.connect(host=self.hostname, user=self.username, password=self.password, database=self.database)
            return  condb
        except Exception as e:
            print("连接异常", e)

#获取的table_columns名称，长度等信息
    def load_columns(self,table_name):
        # 获取数据库连接
        condb = self.connectmysql()
        # 使用cursor() 方法创建一个游标对象 cursor
        cursor = condb.cursor()
        fields = []
        sql = "SELECT c.COLUMN_NAME ,COALESCE(a.ispriamarykey,'N') AS ispriamarykey,case when c.IS_NULLABLE = 'NO' then 'not null' else '' end AS IS_NULLABLE,c.DATA_TYPE,c.CHARACTER_MAXIMUM_LENGTH\
            FROM    [INFORMATION_SCHEMA].[COLUMNS] c\
            left join (SELECT name,'Y' AS ispriamarykey  FROM syscolumns WHERE id=Object_Id('%s') and colid IN(SELECT keyno from sysindexkeys WHERE id=Object_Id('%s'))) a \
            on c.COLUMN_NAME = a.name WHERE   TABLE_NAME = '%s'" % (table_name,table_name,table_name)
        cursor.execute(sql)
        table_info = cursor.fetchall()
        for res in table_info:
            #print(res)
            desc = {
                'column_name': res[0].lower(),
                'table_name': table_name.lower(),
                'type': self._convert_type(res[3]).lower(),
                'length':res[4] ,
                'primary_key': res[1],
                'null':res[2]
            }
            fields.append(desc)
        #print(fields)
        self.postgres_create(fields)