如何在对 SQLite3 的 Python 调用中获取可变长度占位符 [英] How to get variable length placeholders in a Python call to SQLite3

问题描述

有没有办法在 SQL 查询中使用可变长度占位符?

Is there a way to use variable length placeholders in an SQL query?

现在用一个 3 元组，我写的东西是这样的:

Right now with a 3-tuple, I write something like this:

c.execute('SELECT * FROM table WHERE word IN (?, ?, ?)', tup)

但是如果 tup 可以有不同的长度，可能是 4 元组或 2 元组呢?在这种情况下是否有使用占位符的语法?如果不是，编写代码的首选方式是什么?

But what if the tup can be of differing lengths, perhaps a 4-tuple or 2-tuple? Is there a syntax for using placeholders in this situation? If not, what is the preferred way to write the code?

推荐答案

你必须做这样的事情(使用你的例子):

You'd have to do something like this (to use your example):

tup = ... # some sequence/tuple of unknown length
sql = 'SELECT * FROM table WHERE word IN (%s)' % ', '.join('?' for a in tup)
c.execute(sql, tup)

通过这种方式，您可以在 sqlite3 模块解析出来之前动态创建占位符列表并格式化 SQL 字符串.

This way you're dynamically creating the placeholder list and formatting the SQL string before the sqlite3 module parses it out.

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