使用 Python 连接到 Teradata

Question

我正在尝试连接到 teradata 服务器并使用 python 将数据框加载到表中。这是我的代码-

import sqlalchemy 

engine = sqlalchemy.create_engine("teradata://username:passwor@hostname:port/")

f3.to_sql(con=engine, name='sample', if_exists='replace', schema = 'schema_name')

但我收到以下错误 -

InterfaceError: (teradata.api.InterfaceError) ('DRIVER_NOT_FOUND', "No driver found for 'Teradata'.  Available drivers: SQL Server,SQL Server Native Client 11.0,ODBC Driver 13 for SQL Server")

谁能帮我弄清楚我的方法有什么问题？

Answer 1

我不确定您为什么使用 sqlalchemy。但是您可以探索使用 Teradata 模块连接到 Teradata，如另一个链接中所述： Connecting Python with Teradata using Teradata module

Answer 2

要连接teradata数据库，需要pyodbc，我也遇到teradata方言问题。

例子：

import pyodbc

user = 'user'

pasw = 'pass'

host = 'host'

connection = pyodbc.connect('DRIVER=Teradata;DBCNAME=' + host +';UID=' + user + ';PWD=' + pasw +';QUIETMODE=YES', autocommit=True,unicode_results=True)

Answer 3

在 Python 中连接到 Teradata 有多种方法。以下列表并不详尽。

SQLAlchemy

如果你想使用SQLAlchemy，你还需要安装包SQLAlchemy-Teradata。连接方式如下：

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base, DeferredReflection
from sqlalchemy.orm import scoped_session, sessionmaker

[...]

# Connect
engine = create_engine('teradata://' + user + ':' + password + '@' + host + ':22/' + database)
db_session = scoped_session(sessionmaker(autocommit=False, autoflush=False, bind=engine))
db_session.execute('SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;')  # To avoid locking tables when doing select on tables
db_session.commit()

Base = declarative_base(cls=DeferredReflection)
Base.query = db_session.query_property()

然后您可以使用db_session 进行查询。见SQLAlchemy Session API

Pyodbc

如果您想使用Pyodbc，您首先需要在您的机器上安装 Teradata 驱动程序。以我为例，安装 Teradata 驱动程序后，/etc/odbcinst.ini 中有以下条目

[Teradata]
Driver=/opt/teradata/client/16.00/odbc_64/lib/tdata.so
APILevel=CORE
ConnectFunctions=YYY
DriverODBCVer=3.51
SQLLevel=1

然后我可以连接以下内容：

import pyodbc
[...]

#Teradata Connection
connection= pyodbc.connect("driver={Teradata};dbcname=" + host + ";uid=" + user + ";pwd=" + pwd + ";charset=utf8;", autocommit=True)
connection.setdecoding(pyodbc.SQL_CHAR, encoding='utf-8')
connection.setdecoding(pyodbc.SQL_WCHAR, encoding='utf-8')
connection.setdecoding(pyodbc.SQL_WMETADATA, encoding='utf-8')
connection.setencoding(encoding='utf-8')

cursor= n.cursor()
cursor.execute("Select 'Hello World'")
for row in cursor:
    print (row)

Answer 4

我在airflow中遇到了类似的问题，我用jars和jaydebeapi连接teradata数据库并执行sql：

[root@myhost transfer]# cat test_conn.py 
import jaydebeapi
from contextlib import closing


jclassname='com.teradata.jdbc.TeraDriver'
jdbc_driver_loc = '/opt/spark-2.3.1/jars/terajdbc4-16.20.00.06.jar,/opt/spark-2.3.1/jars/tdgssconfig-16.20.00.06.jar'
jdbc_driver_name = 'com.teradata.jdbc.TeraDriver'
host='my_teradata.address'

url='jdbc:teradata://' + host + '/TMODE=TERA'
login="teradata_user_name"
psw="teradata_passwd"

sql = "SELECT COUNT(*) FROM  A_TERADATA_TABLE_NAME where month_key='202009'"


conn = jaydebeapi.connect(jclassname=jdbc_driver_name,
                                  url=url, 
                                  driver_args=[login, psw],
                                  jars=jdbc_driver_loc.split(","))

with closing(conn) as conn:
    with closing(conn.cursor()) as cur:
        cur.execute(sql)
        print(cur.fetchall())
   
[root@myhost transfer]# python test_conn.py
[(7734133,)]
[root@myhost transfer]#