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[英]How to pass tuple in read_sql 'where in' clause in pandas python
[英]How to pass a list of parameter to Pandas read_sql with Teradata
有沒有辦法或如何糾正我的語法,以便將字符串參數列表傳遞到 Pandas 中的 SQL 查詢中? 我有以下代碼,但它不起作用所以我有一個字符串列表,我需要將該列表參數動態傳遞到查詢中
import teradatasql
import pandas as pd
connection = tearadatasql.connect(host="xxx",user="xxx",password="xxx")
column_list = ['A','B','C']
query = """
select column, row
from table1
where column in (%s)
"""
df = pd.read_sql(query, connection, params=column_list)
你應該用一些參數填寫 %s
df = psql.read_sql(('select "column","row" from "table1" '
'where "column" in %(col_list)s'), connection, params={'col_list':column_list})
你有幾個問題:
teradatasql
在你的榜樣拼錯tearadatasql.connect
在您的示例中,您打算綁定column_list
變量中包含的三個值,因此您必須用三個問號參數標記組成 IN 謂詞。
一般來說,您應該動態地組合 IN 謂詞,其中問號參數標記的數量等於您將綁定的參數值列表中的值的數量。
下面是您的示例的修改版本,它更正了這兩個問題。 我實際上運行了這個例子並驗證了它的工作原理。
import teradatasql
import pandas as pd
with teradatasql.connect(host="whomooz",user="guest",password="please") as connection:
with connection.cursor() as cur:
cur.execute("create volatile table table1 (c1 varchar(1), c2 integer) on commit preserve rows")
cur.execute("insert into table1 values ('A', 1) ; insert into table1 values ('B', 2)")
column_list = ['A','B','C']
query = "select c1, c2 from table1 where c1 in ({}) order by c1".format(','.join(['?'] * len(column_list)))
print(query)
print("with params={}".format (column_list))
df = pd.read_sql(query, connection, params=column_list)
print(df)
此示例產生以下輸出:
select c1, c2 from table1 where c1 in (?,?,?) order by c1
with params=['A', 'B', 'C']
c1 c2
0 A 1
1 B 2
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