查询包含退货的入库单（跨月业务-退货处理）

def solve():
    import sqlite3
    import pandas as pd
    
    conn = sqlite3.connect(':memory:')
    
    base_url = 'https://liangdaima.com/static/data/crm/state_05/'
    
    tables = ['suppliers', 'customers', 'products', 
              'stock_in', 'stock_in_items', 
              'stock_out', 'stock_out_items']
    
    for table in tables:
        try:
            url = base_url + table + '.csv'
            df = pd.read_csv(url)
            df.to_sql(table, conn, index=False)
        except Exception as e:
            pass
    
    result = conn.execute('SELECT * FROM stock_in_items WHERE 数量 < 0').fetchall()
    conn.close()
    return result