SQL 输入中的Union问题

请教专家，两个SQL查询Union在SQL输入组件中要怎么写？

(select s.* from ( select *, row_number() over (partition by ALOT_NUMBER order by COMPONENT_PART_ID ) as group_idx  
    from plating_test_04 where MACH_ID='PDF-01') s
where s.group_idx = 1) union (select *, row_number() over (partition by ALOT_NUMBER order by COMPONENT_PART_ID ) as group_idx  
    from plating_test_04 where MACH_ID='PDF-01')

系统报错：Caused by: com.esen.jdbc.pool.impl.mssql.MssqlPooledSQLException: Incorrect syntax near the keyword 'UNION'.

在调试时，我注意到:
整句的SQL语句:  (select s.* from ( select *, row_number() over (partition by ALOT_NUMBER order by COMPONENT_PART_ID ) as group_idx from plating_test_04 WHERE MACH_ID='PDF-01') s where s.group_idx = 1)

两端加上括号会报错：Caused by: com.esen.jdbc.pool.impl.mssql.MssqlPooledSQLException: Incorrect syntax near ')'.
去了括号就可以运行。Union与这个问题有关系吗？

感谢，在线等！