PHP通过PDO连接Oracle时varchar2字段被截断

问题概述：php通过pdo连接oracle后select表varchar2字段被截断字符串，通知报警告Warning: PDOStatement::fetch(): column 2 data was too large for buffer and was truncated to fit it in admin\page.php on line 301
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Oracle10g 10.2.0.4出问题的的这个字段pluname是varchar2(40)，里面数据有中文
PHP通过PDO连接Oracle，执行后这个：pluname这个字段字符串被截断。如下图

oracle中这个字段的情况。如下图：


Warning: PDOStatement::fetch(): column 2 data was too large for buffer and was truncated to fit it in D:\SERVER\WWWROOT\szScm\admin\scmCgNotesBody.php on line 301
提示报错的fetch()代码如下：
[code=php][
$stmt_body = $dbh->prepare("select PluName from table where billno=? order by pluname asc", array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
}
$stmt_body->execute(array($post_billno));
//...
//...
//下面是报错的fetch()
<?php while ($res_body = $stmt_body->fetch()) { ?>
/code]
求高手帮忙