如何在CQL 3预准备语句中绑定IN子句中的值？ [英] How to bind IN-clause values in a CQL 3 prepared statement?

问题描述

我有一个大致类似的表。

I have a table that is roughly like

create table mytable (
   id uuid,
   something text,
   primary key (id)
);

我试图创建一个具有绑定in-子句的预备语句：

I'm trying to create a prepared statement that has a bound in-clause:

PreparedStatement ps = session.prepare("select * from mytable where id IN (?)");
...
UUID[] ids = { uuid1, uuid2, uuid3} ;

无论我如何表示ids绑定，java驱动程序拒绝它们。

No matter how I express the ids to bind, the java driver rejects them.

ps.bind（/ * as array * /）：driver complains语句只有一个值，2提供

ps.bind( /*as array*/): driver complains statement has only one value, 2 supplied

ps.bind（/ *作为逗号分隔的字符串列表uuids * /）：驱动程序抱怨它想要UUID.class对象字符串

ps.bind( /*as comma separated string list of uuids*/): driver complains it wants UUID.class objects, not strings

ps.bind（/ *作为列表对象* /）：驱动程序抱怨它想要UUID.class objs ，而不是List.class对象

ps.bind( /*as list object*/): driver complains it wants UUID.class objs, not a List.class object

我真的希望驱动程序没有期待多少？占位符，因为在列表中有值，因为这意味着你必须重新准备语句每次你想执行它，Datastax文档说不做！

I really hope the driver isn't expecting as many ? place holders as there are values in the in-list, because that means you'd have to reprepare the statement every time you wanted to execute it, which the Datastax docs says not to do!

我看过 com.datastax.driver.core.BoundStatement.bind（）方法，没有任何其他方法可以工作的指示 - 没有魔术包装器或任何东西。

I looked at the com.datastax.driver.core.BoundStatement.bind() method and there is no indication that anything else would work - no magic wrappers or anything.

有办法吗？

推荐答案

正确的语法是 SELECT * FROM mytable WHERE id IN？（不包括？）。这将允许您传递一个UUID列表来绑定到单个查询参数。

The correct syntax is SELECT * FROM mytable WHERE id IN ? (without parens around the ?). This will allow you to pass a list of UUIDs to bind to that single query parameter.

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