下面是伪Python中的一个解决方案：

c = read_next_client()
p = read_next_phone()
while c != None and p != None:
    if c.id == p.id:
        write_combined_record(c,p)
        c = read_next_client()
        p = read_next_phone()
    elif c.id < p.id:
        write_combined_record(c,None)
        c = read_next_client()
    else:
        p = read_next_phone()
while c != None:
    write_combined_record(c,None)
    c = read_next_client()

这里有一些应该非常接近解决方案的东西（不幸的是，我没有实际的文件来测试）。基本思想是同时迭代两个输入文件，根据id字段保持它们同步，并在执行时编写输出文件。

import csv

with (
    open('client.csv', newline='', encoding='utf8-sig') as client_file,
    open('phone.csv', newline='', encoding='utf8-sig') as phone_file,
    open('final.csv', 'w', newline='', encoding='utf8') as final_file,
):
    client_csv = csv.reader(client_file)
    phone_csv = csv.reader(phone_file)
    final_csv = csv.writer(final_file)
    # CSV headers.
    assert next(client_csv) == (
        'id', 'name', 'email', 'contract_number', 'address_id'
    ), 'Bad headers in client.csv'
    assert next(phone_csv) == ('id', 'phone'), 'Bad headers in phone.csv'
    final_csv.writerow(('id', 'phone', 'name', 'email'))
    try:
        # Initialize lookaheads for the two files.
        c_id = ''
        c_id, name, email, _, _ = next(client_csv)
        p_id, phone = next(phone_csv)
        while True:
            if p_id == c_id:
                # Matching row -- merge and advance both files.
                final_csv.writerow((c_id, phone, name, email))
                c_id = ''
                c_id, name, email, _, _ = next(client_csv)
                p_id, phone = next(phone_csv)
            elif int(p_id) > int(c_id):
                # Phone is ahead of client.
                final_csv.writerow((c_id, '', name, email))
                c_id = ''
                c_id, name, email, _, _ = next(client_csv)
            else:
                # Client is ahead of phone.
                p_id, phone = next(phone_csv)
    except StopIteration:
        # We hit the end of one of the files.
        if c_id:
            final_csv.writerow((c_id, '', name, email))
    # Exhaust any remaining entries in client.
    for c_id, name, email, _, _ in client_csv:
        final_csv.writerow((c_id, '', name, email))

可以使用csv.DictReader。您可以打开3个文件-client.csv，phone.csv和final.csv。
然后需要读取client.csv并将其存储在字典中。
然后，您可以迭代phone.csv并检查是否在字典中找到该键。如果找到，则可以使用所需值更新字典。
代码如下-

import csv

csv.field_size_limit(10**5)

with open('client.csv', 'r') as client_file, open('phone.csv', 'r') as phone_file, open('final.csv', 'w', newline='') as final_file:
    client_reader = csv.DictReader(client_file)
    phone_reader = csv.DictReader(phone_file)

    merged_data = {}

    for row in client_reader:
        client_id = row['id']
        merged_data[row_id] = {'id': client_id, 'name': row['name'], 'email': row['email']}

    for row in phone_reader:
        phone_id = row['id']
        if phone_id in merged_data:
            merged_data[phone_id]['phone'] = row['phone']

    csv_writer = csv.DictWriter(final_file, fieldnames=['id', 'phone', 'name', 'email'])
    csv_writer.writeheader()

    for row in merged_data.values():
        writer.writerow(row)