具有多个参数和列表的 Pandas read_sql

Question

我有以下脚本：

now = dt.datetime.now()
date_filter = now - timedelta(days=3)
list_ids = [1,2,3]
dq_connection = mysql.connector.connect(user='user', password='pass', host='localhost', database='db')
engine = create_engine('localhost/db')
cursor = connection.cursor(buffered=True)
query = ('''
SELECT *
FROM (SELECT * FROM myTable1 WHERE id in {%s}
WHERE date >= %s;
''')
df = pd.read_sql_query(query, connection,params=(list_ids,date_filter,))

我想在我的查询中有两个过滤器： 1) 列出我在 list_ids 上的所有 ID 2) 只过滤 date_filter 之前的日期。

第二个过滤器我可以做到，但是当我尝试使用得到的列表时：

pandas.io.sql.DatabaseError: Execution failed on sql

我做错了什么？

Answer 1

因为IN子句接收多个值，你需要用必要数量的占位符调整prepared statement，%s，然后解包func(*list)的参数列表。另外，WHERE 子句都不需要子查询。

query = '''SELECT * FROM myTable1 
           WHERE id in (%s, %s, %s) AND date >= %s;
        '''

df = pd.read_sql_query(query, connection, params=(*list_ids, date_filter))

对于等于列表长度的动态占位符，集成str.join：

placeholders = ", ".join(["%s" for _ in list_ids])

query = '''SELECT * FROM myTable1 
           WHERE id in ({}) AND date >= %s;
        '''.format(placeholders)

df = pd.read_sql_query(query, connection, params=(*list_ids, date_filter))