如何在 Python 中插入新列并将其导出为 CSV？

Question

我有一个按钮可以将数据从 MySQL 导出到 CSV 文件中。获取的数据可能有单行或多行。我想在最左边的列中为每行数据添加一个名为 Item No(Header) 的新列，它的值会根据行数增加。如果有 3 行，则第一行将标记为 1，随后标记为 2 和 3。我的代码执行 SQL 查询以获取数据并将其填充到列表中。然后将值传递给另一个函数以生成并导出 CSV 文件。谁能建议执行此操作的最佳方法？谢谢。

当前输出：期望的输出：

def Company_Excel(asset_Box, ID_Box, newid_Entry, temp_Entry, gps_Entry, current_Entry, PID_Box, projectid_Entry, projectname_Entry, projectpic_Entry, piccontact_Entry, plocation_Entry, name_Entry, company_Entry, email_Entry, contact_Entry, issue_Entry, return_Entry, status_Entry, remarks_Entry, tree, company_Box):

    try:  
        company = company_Box.get()  
        if (company_Box.get() != "Please select one"):
            
            ncommand = ("SELECT `ID`, `Type`, `Project`, `Name`, `Location` from `History` WHERE `Company` = %s ORDER BY `Transaction ID`")
            mycursor.execute(ncommand,(company_Box.get(),))
            nresult = mycursor.fetchall()

            array6 = []
            for e in range(len(nresult)):
                nresult[e] = list(nresult[e])
                array6.append(nresult[e])
                
            write_to_csv_company(array6)
            
            if os.path.exists("Company.csv"):
              os.remove("Company.csv")
            else:
              print("The file does not exist")
              
            tkinter.messagebox.showinfo("Exported", "Success!")

        elif (company_Box.get() == "Please select one"):
            valueErrorMessage = "Please select one from the drop down menu"
            tkinter.messagebox.showerror("Error", valueErrorMessage)
            
        else:
            valueErrorMessage = "Not found, please try again"
            tkinter.messagebox.showerror("Error", valueErrorMessage)
        
    except PermissionError:
            valueErrorMessage = "Please close all the excel files before exporting"
            tkinter.messagebox.showerror("Error", valueErrorMessage)
            
def write_to_csv_company(result):

    with open('Company.csv', 'w+', newline='') as f:
        w = csv.writer(f, dialect='excel')
        for record in result:
            w.writerow(record)
            
    with open('Company.csv',newline='') as f:
        r = csv.reader(f)
        data = [line for line in r]
    
    with open('Items by Company.csv','w',newline='') as f:
        w = csv.writer(f)
        w.writerow(['ID', 'Type', 'Project', 'Name', 'Location'])
        w.writerows(data)

Answer 1

不确定最佳方法。但我建议你可以这样做：

...
array6 = []
for e in range(len(result)):
    array6.append([e+1] + list(nresult[e]))
...
w.writerow(['Item NO', 'ID', 'Type', 'Project', 'Name', 'Location'])
...

Answer 2

import pandas as pd
df=pd.read_csv(yourfile,delimiter="delimiterthatyouhave")
df.insert(0, "Item no", [1,2])
df.to_csv(yourpath, index=False)

您也可以根据 df 的长度生成列表。

Answer 3

你应该远离你的键盘，想想你想做什么。您在数据库中有一些数据，并且有工具可以一次 return 一行。您想要将其导出到 csv 文件（带有标题行）并添加行号作为第一个字段。

一次完成即可：

try:  
    company = company_Box.get()  
    if (company_Box.get() != "Please select one"):
        
        ncommand = ("SELECT `ID`, `Type`, `Project`, `Name`, `Location` from `History` WHERE `Company` = %s ORDER BY `Transaction ID`")
        mycursor.execute(ncommand,(company_Box.get(),))

        with open('Items by Company.csv','w',newline='') as f:
            w = csv.writer(f)
            w.writerow(['Item NO', 'ID', 'Type', 'Project', 'Name', 'Location'])

            for i, row in enumerate(mycursor, 1):
                w.writerow([i] + list(row))
          
        tkinter.messagebox.showinfo("Exported", "Success!")

    elif (company_Box.get() == "Please select one"):
        valueErrorMessage = "Please select one from the drop down menu"
        tkinter.messagebox.showerror("Error", valueErrorMessage)
        
    else:
        valueErrorMessage = "Not found, please try again"
        tkinter.messagebox.showerror("Error", valueErrorMessage)
    
except PermissionError:
        valueErrorMessage = "Please close all the excel files before exporting"
        tkinter.messagebox.showerror("Error", valueErrorMessage)

如何在 Python 中插入新列并将其导出为 CSV？

How to insert a new column and export it to CSV in Python?

python

export-to-csv

mysql-python