How Can I Use a Python List as a Parameter in an SQL `IN` Clause?

Put Python list as parameter in SQL query

In Python development, we often encounter scenarios where we need to integrate data in lists into SQL queries. This often happens when using Python frameworks that follow the ORM (Object Relational Mapping) pattern. This question presents a specific case where a Python list will be used as a filter parameter in a SQL query. The goal is to retrieve data for all elements in the list.

To achieve this, a common approach is to parameterize the query, using placeholders that will be replaced with list values ​​during execution. This not only enhances code readability, but also prevents potential security vulnerabilities associated with string concatenation.

Consider the following code snippet:

<code class="language-python">l = [1, 5, 8]

placeholder = '?'  # 根据使用的数据库API调整占位符。
placeholders = ', '.join([placeholder for _ in l])

query = 'SELECT name FROM students WHERE id IN (%s)' % placeholders
cursor.execute(query, l)</code>

By using parameterization, even values ​​that may require special handling (such as strings) can be seamlessly integrated into the query without the need for escaping. This approach provides a powerful and reliable mechanism for adding Python lists to SQL queries.

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