db2 中的 sysibm.sysdummy1 和mysql oracle中的dual

db2 中的 sysibm.sysdummy1 和mysql oracle中的dual是一樣的吧？  

先留着這個問題，下次再查

但是下面語句在DB2中可以運行，但是在oracle中報錯[Err] 1146 - Table 'sysibm.dual' doesn't exist

SELECT count(*)
  FROM iplat.XS_USER_GROUP
 where 1 = 1
   and group_ename != 'ADMIN'
   and group_ename != 'root'
   and group_ename != 'managerRoot'
   AND id not in (SELECT DISTINCT MEMBER_ID
                    FROM iplat.XS_USER_GROUP_MEMBER
                   WHERE MEMBER_TYPE = 'USER_GROUP'
                     and PARENT_ID = 'root'
                     and MEMBER_ID is not null
                  union
                  select 'root' from sysibm.sysdummy1)

把sysibm.sysdummy1 改成 dual 就可以運行了

SELECT count(*)
  FROM iplat.XS_USER_GROUP
 where 1 = 1
   and group_ename != 'ADMIN'
   and group_ename != 'root'
   and group_ename != 'managerRoot'
   AND id not in (SELECT DISTINCT MEMBER_ID
                    FROM iplat.XS_USER_GROUP_MEMBER
                   WHERE MEMBER_TYPE = 'USER_GROUP'
                     and PARENT_ID = 'root'
                     and MEMBER_ID is not null
                  union
                  select 'root' from dual)