统计某一日期之前发生的次数

-- 示例SQL查询
SELECT COUNT(*) 
FROM events 
WHERE event_date < '2023-01-01';

# 示例Python代码
import pandas as pd

# 假设df是一个包含event_date列的DataFrame
df = pd.read_csv('events.csv')
count = df[df['event_date'] < '2023-01-01'].shape[0]
print(count)

# 示例Python代码处理不同日期格式
from datetime import datetime

def parse_date(date_str):
    for fmt in (('%Y-%m-%d', '%d/%m/%Y'),):
        try:
            return datetime.strptime(date_str, fmt)
        except ValueError:
            continue
    raise ValueError('no valid date format found')

df['event_date'] = df['event_date'].apply(parse_date)
count = df[df['event_date'] < datetime(2023, 1, 1)].shape[0]
print(count)