如何使用python使用mssql+pyodbc连接字符串创建和删除数据库答案

【问题标题】：How to create and delete database using mssql+pyodbc connection string using python如何使用python使用mssql+pyodbc连接字符串创建和删除数据库
【发布时间】：2020-02-24 13:15:37
【问题描述】：

我有一个如下的数据库引擎：

from sqlalchemy import create_engine
import pydoc

# connect db
engine = create_engine('mssql+pyodbc://xxxx\MARTRNO_EXPRESS/toolDB?driver=SQL+Server+Native+Client+11.0')
connection = engine.connect()

我尝试使用类似下面的代码来创建一个数据库，使用这个连接作为下面的代码：

from database import connec
import pandas as pd

def delete_all_tables_from_db():
    delete_all_tables_query = "CREATE DATABASE MyNewDatabase"

    delete_all_tables_df = pd.read_sql(delete_all_tables_query, connec.engine)
    connec.engine.execute(delete_all_tables_df)

delete_all_tables_from_db()

但我发现这个错误：

Traceback (most recent call last):
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 1245, in _execute_context
    self.dialect.do_execute(
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\default.py", line 588, in do_execute
    cursor.execute(statement, parameters)
pyodbc.ProgrammingError: ('42000', '[42000] [Microsoft][SQL Server Native Client 11.0][SQL Server]CREATE DATABASE statement not allowed within multi-statement transaction. (226) (SQLExecDirectW)')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:/Users/haroo501/PycharmProjects/ToolUpdated/database/delete_all_tables_from_db.py", line 10, in <module>
    delete_all_tables_from_db()
  File "C:/Users/haroo501/PycharmProjects/ToolUpdated/database/delete_all_tables_from_db.py", line 7, in delete_all_tables_from_db
    delete_all_tables_df = pd.read_sql(delete_all_tables_query, connec.engine)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\pandas\io\sql.py", line 432, in read_sql
    return pandas_sql.read_query(
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\pandas\io\sql.py", line 1218, in read_query
    result = self.execute(*args)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\pandas\io\sql.py", line 1087, in execute
    return self.connectable.execute(*args, **kwargs)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 2182, in execute
    return connection.execute(statement, *multiparams, **params)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 976, in execute
    return self._execute_text(object_, multiparams, params)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 1143, in _execute_text
    ret = self._execute_context(
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 1249, in _execute_context
    self._handle_dbapi_exception(
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 1476, in _handle_dbapi_exception
    util.raise_from_cause(sqlalchemy_exception, exc_info)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\util\compat.py", line 398, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\util\compat.py", line 152, in reraise
    raise value.with_traceback(tb)
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\base.py", line 1245, in _execute_context
    self.dialect.do_execute(
  File "C:\Users\haroo501\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\engine\default.py", line 588, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.ProgrammingError: (pyodbc.ProgrammingError) ('42000', '[42000] [Microsoft][SQL Server Native Client 11.0][SQL Server]CREATE DATABASE statement not allowed within multi-statement transaction. (226) (SQLExecDirectW)')
[SQL: CREATE DATABASE MyNewDatabase]
(Background on this error at: http://sqlalche.me/e/f405)

Process finished with exit code 1

我试图修改这个数据库并且工作正常，但我必须假设使用权限。

我正在使用 MicroSoft SQL Managment Studio SQL EXPRESS：

服务器类型Database Engine
身份验证Windows Authentication我没有数据库的用户名和密码

我认为现在这部分的问题：

'mssql+pyodbc://xxxx\SMARTRNO_EXPRESS/toolDB?driver=SQL+Server+Native+Client+11.0'

我使用这个数据库连接字符串直接连接到toolDB

所以我需要像下面这样的连接字符串：

# connect db
engine = create_engine('mssql+pyodbc://xxxx\SMARTRNO_EXPRESS?driver=SQL+Server+Native+Client+11.0')
connection = engine.connect()

能够在此服务器上创建数据库，并且能够删除或创建甚至修改数据库

【问题讨论】：

Pandas read_sql 通常期望结果集从 SELECT 返回，而不是像 CREATE DATABASE 这样的操作 DDL 语句，想到它可能不是您想在 Python 等应用程序脚本中运行的语句。数据库是预先设计和计划的资源，而不是动态运行事件。顺便说一句 - SQLAlchemy 引擎可以运行任何 SQL 语句（DDL 或 DML）。
@Parfait 非常感谢您的评论，它对我有很大帮助。我理解您的意思是我可以使用SELECT 而不是CREATE 更好？你能举个例子吗，我喜欢:)
@Parfait 如何使用SELECT 代替CREATE、ALTER 和DROP？ :)
@Parfait 你的意思是这样的def create_db(): create_bd_query = "SELECT DATABASE toolDB" select_result = connec.conn.execute(create_bd_query) return select_result
最终，这取决于您要做什么。使用 pandas 导入或导出数据表结果。对于其他操作，请使用pyodbc 游标连接或SQLAlchemy 引擎连接。再一次，我会避免在 Python 中创建数据库。使用 Management Studio 或 sqlcmd 在服务器上执行该高级命令一次。

标签： python sql-server sql-server-express pypyodbc

【解决方案1】：

好吧！我通过在database .py 文件中创建一个新连接来解决这个问题，如下代码所示，并添加autocommit = True：

conn = pyodbc.connect("driver={SQL Server};server=WINKPN-3B5JTT2\SMARTRNO_EXPRESS; database=master; trusted_connection=true",
                      autocommit=True)

并尝试通过以下代码访问此连接：

from database import connec

def create_all_tables_from_db():
    create_all_tables_query = "CREATE DATABASE MyNewDatabase"
    connec.conn.execute(create_all_tables_query)

create_all_tables_from_db()

【讨论】：