sql1:select*fromtwhereaisnotnullorderbya;sql2:select*fromtwhereaisnullorderbyb;sql1unionallsql2;sql1和sql2分别查询的时候是正确的，unionall后顺序就打乱了，怎么才能让他保持... sql1:select * from t where a is not null order by a;
sql2:select * from t where a is null order by b;
sql1 union all sql2;
sql1和sql2分别查询的时候是正确的，union all 后顺序就打乱了，怎么才能让他保持原来的顺序呢？即：先显示sql1的结果集，再显示sql2的结果集