【测试类型：接口功能】【测试版本：6.0.0】 JDBC调用getObject()/getColumnType()获取cast(负数 as time)值报错

【操作系统和硬件信息】(查询命令: cat /etc/system-release, uname -a):
CentOS Linux release 7.6.1908 (Core)
Linux kwepwebenv03026 3.10.0-1062.el7.x86_64 #1 SMP Wed Aug 7 18:08:02 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

【测试环境】(单机/1主x备x级联备):单机

【被测功能】:JDBC驱动支持MySQL全量数据类型兼容性测试

【测试类型】:功能测试

【数据库版本】(查询命令: gaussdb -V):
(openGauss 6.0.0 build 4614510e) compiled at 2024-01-17 14:47:18 commit 0 last mr on x86_64-unknown-linux-gnu, compiled by g++ (GCC) 10.3.0, 64-bit

【预置条件】:数据库正常运行，兼容B库已创建

【操作步骤】(请填写详细的操作步骤):
1.编译java脚本（见附件），执行以下sql语句
--step1:建表;expect:成功
drop table if exists t_mediumint0005;
create table t_mediumint0005(
c1 int,
c2 mediumint,
c3 mediumint(1),
c4 mediumint(255),
c5 mediumint default '10',
c6 mediumint auto_increment primary key,
c7 mediumint(1) default 0,
c8 mediumint(10) not null default 99,
c9 mediumint unique);

--step2:插入数据;expect:成功

set @val = '111111';
insert t_mediumint0005 values(
1, @val, @val, @val, @val, @val, @val, @val, @val);
set @val = '990909' + 1;
insert t_mediumint0005 values(
2, @val, @val, @val, @val, @val, @val, @val, @val);
set @val = 202211;
insert t_mediumint0005 values(
3, @val, @val, @val, @val, @val, @val, @val, @val);
set @val = -11;
insert t_mediumint0005 values(
4, @val, @val, @val, @val, @val, @val, @val, @val);
set @val = 11;
insert t_mediumint0005 values(
5, @val, @val, @val, @val, @val, @val, @val, @val);

--step3:查询表数据;expect:成功
select * from t_mediumint0005 order by 1;
select c1, cast(c2 as time), cast(c3 as time), cast(c4 as time), cast(c5 as
time), cast(c6 as time), cast(c7 as time), cast(c8 as time), cast(c9 as time)
from t_mediumint0005 where c1<>2 order by 1;
2.执行java脚本

【预期输出】:
1.执行成功
2.执行成功，输出结果与mysql一致

【实际输出】:
1.执行成功
2.报错、

getObject方法：
mysql

opengauss

getColumnType方法：
msyql

openGauss

getString方法：
mysql

openGauss

【原因分析】:

1. 这个问题的根因
2. 问题推断过程
3. 还有哪些原因可能造成类似现象
4. 该问题是否有临时规避措施
5. 问题解决方案
6. 预计修复问题时间

【日志信息】(请附上日志文件、截图、coredump信息):

【测试代码】: