在mysql5.5上通过JDBC创建触发器时出错

Question

这是我的代码：

triggerBuilder.append("DROP TRIGGER IF EXISTS `insert_associated_inquiry`; ");
triggerBuilder.append(" DELIMITER %% ");

triggerBuilder.append(" CREATE TRIGGER insert_associated_inquiry BEFORE UPDATE ON inquiry ");
triggerBuilder.append(" FOR EACH ROW Begin ");

triggerBuilder.append(" insert into associated_inquiries(inquiry_id , subject , content , inquiry_date , preferred_date ) " );
triggerBuilder.append("values");
        triggerBuilder.append(" ( " );
            triggerBuilder.append(" OLD.id , ");
            triggerBuilder.append(" OLD.subject , " );
            triggerBuilder.append(" OLD.content , " );
            triggerBuilder.append(" OLD.created_on , " );
            triggerBuilder.append(" OLD.preffered_date " );
        triggerBuilder.append(" ) ; ");

triggerBuilder.append(" END %% ");

triggerBuilder.append(" DELIMITER ; ");

con.createStatement().execute(triggerBuilder.toString());

这就是抛出的错误：

 com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: 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 'DELIMITER %%  CREATE TRIGGER insert_associated_inquiry 
 BEFORE UPDATE ON inquiry ' at line 1

可能是此错误的原因和解决方案。请帮助。谢谢。

Answer 1

不要在JDBC和MySQL中使用定界符。分隔符仅由MySQL控制台使用，以便它可以告知您键入的触发器，存储过程等何时结束。在JDBC中，您将整个SQL字符串放在一起，然后将其发送到数据库。因为您可以控制何时将SQL发送到数据库，所以不需要使用定界符。

我从代码中删除了这两DELIMITER行和%%定界符的使用，并将DROP TRIGGER命令分别发送到数据库。我剩下的代码如下：

con.createStatement().execute("DROP TRIGGER IF EXISTS `insert_associated_inquiry`");

triggerBuilder.append(" CREATE TRIGGER insert_associated_inquiry BEFORE UPDATE ON inquiry ");
triggerBuilder.append(" FOR EACH ROW Begin ");

triggerBuilder.append(" insert into associated_inquiries(inquiry_id , subject , content , inquiry_date , preferred_date ) " );
triggerBuilder.append("values");
        triggerBuilder.append(" ( " );
            triggerBuilder.append(" OLD.id , ");
            triggerBuilder.append(" OLD.subject , " );
            triggerBuilder.append(" OLD.content , " );
            triggerBuilder.append(" OLD.created_on , " );
            triggerBuilder.append(" OLD.preffered_date " );
        triggerBuilder.append(" ) ; ");

triggerBuilder.append(" END ");

con.createStatement().execute(triggerBuilder.toString());

该代码似乎有效，因为无论触发器是否存在，我都可以无错误地运行此代码。如果触发器先前不存在，则会创建它。