使用cx_Oracle将变量绑定到表名
我在Python中使用cx_Oracle，无法将变量用作表名，例如以下简单示例：
I'm using cx_Oracle in Python and can't get a variable be used as table name, like in this simple example:
query = "select * from some.:usertable.userinfo"
bindvars = {'usertable':usertable}
cursor.execute(query, bindvars)
正确的语法是什么？当我使用 WHERE …等但不是与表名一起使用时，变量替换可以很好地工作。我想我必须以某种方式分隔：usertable ...
What is the correct syntax? Variable substition works fine when I use WHERE… etc. but not with table names. I guess I have to separate ":usertable" somehow…
数据库适配器很少支持将参数用于不是价值（需要引用的内容）。要么使用字符串格式设置（狡猾，就会冒着注入SQL的危险），要么使用像SQLAlchemy这样的库，让您使用Python代码生成有效的SQL。
Database adapters rarely support using parameters for anything that isn't a 'value' (something that needs quoting). Either use string formatting (dodgy, you run the risk of a sql injection) or use a library like SQLAlchemy that let's you produce valid SQL using Python code.
如果确定您的 usertable 值是合理的（例如，对照现有表名列表进行检查），则可以执行以下操作：
If you are certain your usertable value is sane (checked against a list of existing table names, for example), the following would work:
query = 'select * from some.{usertable}.userinfo'.format(usertable=usertable)