使用 python 将 SQL 输出数据更新到相应工作表中的现有 Excel

Question

我是 Python 编程新手，正在寻求一些帮助/指导来纠正我的 Python 代码。

这是我的查询。

1. 我有一个 Excel 文件，其中包含（7 个标签）。
2. 我有一个文件夹，其中包含 7 个不同的文本文件，每个文本文件都包含各自的选项卡 SQL 查询，每个文本文件名与 Excel 文件中的选项卡名称相同。

我编写了一个 Python 代码来逐个循环遍历所有文本文件并执行每个文本文件 SQL 查询以及将输出的任何数据，输出数据应转储到相应工作表/选项卡中的现有 excel 文件中.我正在使用 pandas 来执行此操作，但是，代码运行良好，但是在将数据更新到 excel 时，pandas 正在从文件中删除所有现有工作表，并且仅将当前输出数据更新到 excel 文件中。

示例：如果 Python 代码执行一个文本文件（文件名：数据），在执行此 SQL 查询后，我们得到了一些数据，这些数据应转储到 excel 文件（工作表名：数据）中。

<pre><code>
import pypyodbc
import pandas as pd
import os
import ctypes
from pandas import ExcelWriter
fpath = r"C:\MNaveed\DataScience\Python Practice New\SQL Queries"
xlfile = r"C:\MNaveed\DataScience\Python Practice New\SQL Queries\Open_Case_Data.xlsx"
cnxn = pypyodbc.connect('Driver={SQL Server};Server=MyServerName;Database=MyDatabaseName;Trusted_Connection=Yes')
cursor = cnxn.cursor()

for subdir, dirs, files in os.walk(fpath):
    for file in files:
        #print(os.path.join(subdir,file))
        filepath = os.path.join(subdir,file)
        #print("FilePath: ", filepath)

        if filepath.endswith(".txt"):
            if file != "ClosedAging_Cont.txt":
                txtdata = open(filepath, 'r')
                script = txtdata.read().strip()
                txtdata.close()
                cursor.execute(script)
                if file == "ClosedAging.txt":
                    txtdata = open(os.path.join(subdir,"ClosedAging_Cont.txt"), 'r')
                    script = txtdata.read().strip()
                    txtdata.close()
                    cursor.execute(script)

                col = [desc[0] for desc in cursor.description]
                data = cursor.fetchall()
                df = pd.DataFrame(list(data),columns=col)

                #save_xls(df,xlfile)

                writer = pd.ExcelWriter(xlfile)
                flnm = file.replace('.txt','').strip()
                df.to_excel(writer,sheet_name=flnm,index=False)
                writer.save()

                print(file, " : Successfully Updated.")
            else:
                print(file, " : Ignoring this File")
        else:
            print(file, " : Ignoring this File")

ctypes.windll.user32.MessageBoxW(0,"Open Case Reporting Data Successfully Updated","Open Case Reporting",1)
</pre></code>

Answer 1

通过循环遍历文本文件，您每次都会覆盖循环内的 Excel 文件。而是实例化 pd.ExcelWriter(xlfile) 并在循环外调用 writer.save() 。

以下示例改编自xlswriter documentation

您可以在此处找到有关多张工作表的更多信息：xlswriter documentaion - multiple sheets

import pandas as pd

# Create a Pandas Excel writer using XlsxWriter as the engine outside the loop.
writer = pd.ExcelWriter('pandas_simple.xlsx', engine='xlsxwriter')
# Sample loop, replace with directory browsing loop
for i in range(7):
    # Sample Pandas dataframe. Replace with SQL query and resulting data frame.
    df = pd.DataFrame({'DataFromSQLQuery': ['SQL query result {0}'.format(i)]})
    # Convert the dataframe to an XlsxWriter Excel object.
    df.to_excel(writer, sheet_name='Sheet{0}'.format(i))
# Close the Pandas Excel writer and output the Excel file.
writer.save()

以下代码解决了具体问题，但未经测试。

import pypyodbc
import pandas as pd
import os
import ctypes
from pandas import ExcelWriter

fpath = r"C:\MNaveed\DataScience\Python Practice New\SQL Queries"
xlfile = r"C:\MNaveed\DataScience\Python Practice New\SQL Queries\Open_Case_Data.xlsx"
cnxn = pypyodbc.connect('Driver={SQL Server};Server=MyServerName;Database=MyDatabaseName;Trusted_Connection=Yes')
cursor = cnxn.cursor()

# Create a Pandas Excel writer using XlsxWriter as the engine outside the loop
writer = pd.ExcelWriter('pandas_simple.xlsx', engine='xlsxwriter')

# File loop
for subdir, dirs, files in os.walk(fpath):
    for file in files:
        filepath = os.path.join(subdir,file)
        if filepath.endswith(".txt"):
            if file != "ClosedAging_Cont.txt":
                txtdata = open(filepath, 'r')
                script = txtdata.read().strip()
                txtdata.close()
                cursor.execute(script)
                if file == "ClosedAging.txt":
                    txtdata = open(os.path.join(subdir,"ClosedAging_Cont.txt"), 'r')
                    script = txtdata.read().strip()
                    txtdata.close()
                    cursor.execute(script)

                col = [desc[0] for desc in cursor.description]
                data = cursor.fetchall()

                # Data frame from original question
                df = pd.DataFrame(list(data),columns=col)

                # Convert the dataframe to an XlsxWriter Excel object
                flnm = file.replace('.txt','').strip()
                df.to_excel(writer, sheet_name=flnm, index=False)

                print(file, " : Successfully Updated.")
            else:
                print(file, " : Ignoring this File")
        else:
            print(file, " : Ignoring this File")

# Close the Pandas Excel writer and output the Excel file
writer.save()

ctypes.windll.user32.MessageBoxW(0,"Open Case Reporting Data Successfully Updated","Open Case Reporting",1)