如何防止PDO将问号解释为占位符? [英] How to prevent PDO from interpreting a question mark as a placeholder?

问题描述

要检测 hstore 中密钥的存在，我需要运行查询像这样:

For detecting the existence of a key in a hstore, I need to run a query like this:

SELECT * FROM tbl WHERE hst ? 'foo'

但是，这给了我一个PDOException:

However, that gives me a PDOException:

PDOException: SQLSTATE[HY093]: Invalid parameter number: no parameters were bound: SELECT * FROM tbl WHERE hst ? 'foo'

是否有任何方法可以逃脱问号，以便PDO不会将其用作占位符?我尝试使用最多四个反斜杠以及一个双问号(??)，但似乎没有什么说服PDO留下问号的.

Is there any way to escape the question mark so PDO won't pick it up as a placeholder? I've tried with up to four backslashes, as well as a double question mark (??), but nothing seems to persuade PDO to leave the question mark alone.

推荐答案

使用函数调用表单.根据系统目录，hstore ?运算符使用exist函数:

Use the function call form. According to the system catalogs, the hstore ? operator uses the exist function:

regress=# select oprname, oprcode from pg_operator where oprname = '?';
 oprname | oprcode 
---------+---------
 ?       | exist
(1 row)

因此您可以写:

SELECT * FROM tbl WHERE exist(hst,'foo');

(个人而言，我不是hstore以操作员为中心的设计和文档的忠实拥护者，我认为它放弃了基于函数的接口的有用的自文档化属性，而没有任何真正的好处，我通常使用其函数调用而不是其运算符.仅仅因为您可以定义运算符并不意味着您应该这样做.)

(Personally I'm not a big fan of hstore's operator-centric design and documentation, I think it discards the useful self-documenting properties of a function based interface without any real benefit and I usually use its function calls rather than its operators. Just because you can define operators doesn't mean you should.)

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