在 SQL 查询中使用 Python 列表获取列名 [英] Use Python list in SQL query for column names
问题描述
我在 Python 列表中有一堆列名.现在我需要使用该列表作为 SELECT
语句中的列名.我该怎么做?
I have a bunch of column names in a Python list. Now I need to use that list as the column names in a SELECT
statement. How can I do that?
pythonlist = ['one', 'two', 'three']
SELECT pythonlist FROM data;
到目前为止我有:
sql = '''SELECT %s FROM data WHERE name = %s INTO OUTFILE filename'''
cur.execute(sql,(pythonlist,name))
推荐答案
您不能将要选择的列列表作为参数传递给 cur.execute
.它应该是您的 SQL 表达式的一部分,例如:
You cannot pass list of columns to select as a parameter to cur.execute
. It should be part of your SQL expression, something like:
sql = "SELECT " + ",".join(pythonlist) + " FROM data WHERE name = %s INTO OUTFILE filename"
cur.execute(sql, (name,))
需要注意的一件事是 SQL 中参数值的占位符取决于数据库.如果 %s
不起作用,请尝试使用 ?
或 :1
.请参阅 https://www.python.org/dev/peps/pep-0249/#paramstyle 了解更多详情.
One thing to be aware of is that placeholder for a parameter value in the SQL depends on the database. If %s
doesn't work try using ?
or :1
. See https://www.python.org/dev/peps/pep-0249/#paramstyle for more details.
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