从 Microsoft SQL 查询到 Pandas 数据框

Question

我正在尝试用 Python3 编写一个程序，该程序将在 Microsoft SQL 中的表上运行查询并将结果放入 Pandas DataFrame。

我的第一次尝试是下面的代码，但由于某种原因，我不明白这些列没有按照我在查询中运行它们的顺序出现，它们出现的顺序以及它们作为结果改变，填满了我的程序的其余部分：

 import pandas as pd, pyodbc    

    result_port_mapl = []

    # Use pyodbc to connect to SQL Database
    con_string = 'DRIVER={SQL Server};SERVER='+ <server> +';DATABASE=' + 
<database>


     cnxn = pyodbc.connect(con_string)
    cursor = cnxn.cursor()

    # Run SQL Query
    cursor.execute("""
                   SELECT <field1>, <field2>, <field3>
                   FROM result
                   """)

    # Put data into a list
    for row in cursor.fetchall():
        temp_list = [row[2], row[1], row[0]]
        result_port_mapl.append(temp_list)

    # Make list of results into dataframe with column names
    ## FOR SOME REASON HERE row[1] AND row[0] DO NOT CONSISTENTLY APPEAR IN THE 
    ## SAME ORDER AND SO THEY ARE MISLABELLED
    result_port_map = pd.DataFrame(result_port_mapl, columns={'<field1>', '<field2>', '<field3>'})

我也试过下面的代码

    import pandas as pd, pyodbc

    # Use pyodbc to connect to SQL Database
    con_string = 'DRIVER={SQL Server};SERVER='+ <server> +';DATABASE=' + <database>
    cnxn = pyodbc.connect(con_string)
    cursor = cnxn.cursor()

    # Run SQL Query
    cursor.execute("""
                   SELECT <field1>, <field2>, <field3>
                   FROM result
                   """)

    # Put data into DataFrame
    # This becomes one column with a list in it with the three columns 
    # divided by a comma
    result_port_map = pd.DataFrame(cursor.fetchall())

    # Get column headers
    # This gives the error "AttributeError: 'pyodbc.Cursor' object has no 
    # attribute 'keys'"
    result_port_map.columns = cursor.keys()

如果有人能提出这些错误发生的原因或提供更有效的方法，将不胜感激。

谢谢

Answer 1

如果你只使用 read_sql?喜欢：

import pandas as pd, pyodbc    
con_string = 'DRIVER={SQL Server};SERVER='+ <server> +';DATABASE=' + <database>
cnxn = pyodbc.connect(con_string)
query = """
  SELECT <field1>, <field2>, <field3>
  FROM result
"""
result_port_map = pd.read_sql(query, cnxn)
result_port_map.columns.tolist()