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Python 3.5.2，标准库 sqlite3。

我正在尝试在子句中的IN运算符中使用动态标准发出 SQL 查询：WHERE

错误的代码（不起作用）

def top_item_counts_in_installations(cursor, installation_names):
    return cursor.execute(
        "SELECT itm.name, COUNT(*)"
        " FROM Installations ins INNER JOIN Items itm ON itm.id=ins.itmid"
        " WHERE ins.name IN (?)"
        " GROUP BY itm.name"
        " ORDER BY COUNT(*) DESC"
        " LIMIT 3",
        (installation_names,))

installation_names是一个元组，但上面显然不起作用，有错误

sqlite3.InterfaceError: Error binding parameter 0 - probably unsupported type.

所以我目前做的是根据长度准备一系列参数持有者installation_names：

kludge（工作但丑陋）

def top_item_counts_in_installations(cursor, installation_names):
    param_holders= ",".join("?" for i in installation_names)
    return cursor.execute(
        "SELECT itm.name, COUNT(*)"
        " FROM Installations ins INNER JOIN Items itm ON itm.id=ins.itmid"
        " WHERE ins.name IN (%s)"
        " GROUP BY itm.name"
        " ORDER BY COUNT(*) DESC"
        " LIMIT 3" % param_holders,
        installation_names)

有没有合适的方法来参数化正确的术语IN而不是我的 kludge？我还没有设法在文档中找到任何东西。

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0 回答 0