执行sql返回Error Number: 1064

ci_user

大家好，我是纯粹新手
我使用以下语句

PHP复制代码

$sql = " SELECT @maxorder := CASE WHEN  MAX(displayorder) IS NULL THEN 0 ELSE MAX(displayorder) END
                                FROM activitycategory
                                WHERE parentcategoryid = ?;  
                                INSERT INTO activitycategory(categoryname, parentcategoryid, status, displayorder)
                                VALUES (?, ?, 1, @maxorder +1) ";
       
                $this->db->query($sql, array($parentcategoryid, $categoryname, $parentcategoryid));

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返回错误是：

A Database Error OccurredError Number: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' INSERT INTO activitycategory(categoryname, parentcategoryid, status, dis' at line 3
SELECT @maxorder := CASE WHEN MAX(displayorder) IS NULL THEN 0 ELSE MAX(displayorder) END FROM activitycategory WHERE parentcategoryid = 24, INSERT INTO activitycategory(categoryname, parentcategoryid, status, displayorder) VALUES ('test3', 24, 1, @maxorder +1)
Filename: D:\wamp\www\system\database\DB_driver.php
Line Number: 330

我把上面的sql单独放在mysql中执行可以成功，请求高手帮助，谢谢

gaoomei

这是什么sql语法啊···
看不懂啊··

ci_user

简单来说，取一个表中最大的displayorder赋给变量@maxorder，然后在这个表中插入一条新数据，displayorder ＝ @maxorder+ 1

可ci就是不成功啊不成功