Re: Prepare Statement

Hmm, intersting.
I am using jdk 1.3.1, and pg74.213.jdbc2.jar driver, I hope this bug
could be fixed in later version.

Thanks.



Jie Liang

-----Original Message-----
From: Kris Jurka [mailto:books@ejurka.com]
Sent: Thursday, June 17, 2004 3:26 PM
To: Jie Liang
Cc: Tom Lane; pgsql-sql@postgresql.org; pgsql-jdbc@postgresql.org
Subject: Re: [JDBC] Prepare Statement




On Thu, 17 Jun 2004, Jie Liang wrote:

> Kris,
> You are right, I modified that piece of code a little bit,
> CallableStatement stmt = conn.prepareCall("{?=call chr(?)}"); Then my
> log file were: Select * from chr(65) as result;
> Select * from chr(66) as result;
> ......
> However, if I use:
> PrepareStatement stmt = conn.prepareStatement("SELECT chr(?)");
> Then my log file are same as yours.i.e. it use PREPARE and EXECUTE.
>
> So, I am getting confusion.
> I think CallableStatement is extended from PrepareStatement, it should

> have same behaviou.
>

What's happening here is that you can only use prepared statements for
certain operations.  You can't for example prepare a CREATE TABLE
statement.  The driver examines the query to see if it is valid for
preparing and I believe the problem here is that with a callable
statement
it is examinging the query with "call" before it is transformed to a
SELECT, so it doesn't recognize it as a preparable.  This looks like a
bug
to me.

Kris Jurka