Exclude null values ​​when Oracle limits

1.Oracle特性

Oracle有个特性,just when limited,Null values ​​are also excluded:
例如:

select '小黑'name,'2'class from dual
union all select '小白'name,'0'class from dual
union all select '小红'name,'1'class from dual
union all select '小绿'name,'4'class from dual
union all select null name,'5' class from dual

If you exclude black,Then you will get data like this:

select * from (select '小黑'name,'2'class from dual
union all select '小白'name,'0'class from dual
union all select '小红'name,'1'class from dual
union all select '小绿'name,'4'class from dual
union all select null name,'5' class from dual)where name<>'小黑'

The database excludes the data of Xiaohei at the same time,也将class为5data were also excluded

2.解决

The problem is also solved very well,Just add it after the limitor name is null,即可:

select * from (select '小黑'name,'2'class from dual
union all select '小白'name,'0'class from dual
union all select '小红'name,'1'class from dual
union all select '小绿'name,'4'class from dual
union all select null name,'5' class from dual)where name<>'小黑' or name is null