使用Python读取SQL表时丢失列名

Question

我正在从SQL Server读取非常大的表（大约是我的RAM的3倍）并将它们作为.csv写入块中。但是在.csv文件中缺少列名。我做错了什么？

我的代码如下：

import pandas as pd
import pyodbc

cnxn = pyodbc.connect('''Driver={SQL Server}; Server=myServer; > Database=myDb''')
cursor = cnxn.cursor()

#Extracting the naems of all the tables in the database
cursor.execute("select * from information_schema.tables")
tables = cursor.fetchall()
cursor.close()
#Reading all the tables and saving them chunk by chunk as csv
counter = 1
for t in tables:
   print("Currently working on table Number {0} - {1}".format(counter, t[2]))
   cursor = cnxn.cursor()
   cursor.execute("Select * from {0}".format(t[2]))

    file_name = "{0}.csv".format(t[2])
    f = open(file_name, 'w')
    # Get data in batches
    while True:
        # Read the data
        df = pd.DataFrame(cursor.fetchmany(1000))
        # We are done if there are no data
        if len(df) == 0:
            break
        # Let's write to the file
        else:
            df.to_csv(f, header=False)

    counter += 1
    f.close()
    cursor.close()

cnxn.close()