为什么pi()函数在使用其JDBC驱动程序的Oracle中不起作用? [英] Why pi() function does not work in Oracle using its JDBC driver?

问题描述

查询1可以与Oracle JDBC驱动程序配合使用，但查询2则不能.我不明白为什么.拜托，有人可以帮我吗?

Query 1 works fine with the Oracle JDBC driver but Query 2 doesn't. I don't understand why. Please, could someone help me?

查询1:

SELECT {fn pi()} FROM table;

查询2:

SELECT pi() FROM table;

推荐答案

Oracle中没有本机pi()函数. JDBC驱动程序将简单地将其替换为硬编码值.

There is no native pi() function in Oracle. The JDBC driver will simply replace that with a hardcoded value.

如果您运行

SELECT {fn pi()} FROM dual;

驱动程序将发送:

SELECT ( 3.141592653589793238462643383279502884197169399375 ) 
FROM
 dual

到服务器-这就是为什么即使没有可用的功能也可以对Oracle数据库使用{fn pi()}的原因.

to the server - that's why you can use the {fn pi()} against an Oracle database even though there is no such function available.

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