Question: In this below example why other than "NAME1" all giving null as result in oracle 11g.

If I mention space explicitly it takes space otherwise null only not empty string.Please help me to clarify this.

In NAME2 I specify the empty space but still it gives null.

```
select 
NVL(NAME,' ') AS NAME1,
NVL(NAME,'') AS NAME2,
NVL(NAME,NULL) AS NAME3,
NAME AS NAME4 
from employee

```

**OUTPUT :**

(space),null,null,null

Answer: 
Because '' is equal with null in oracle. For example these two queries are same:

```
update  test set name=''  where id = 15
update  test set name=null   where id = 15

```
The reason is that in Oracle an empty string is equivalent to `NULL`.

You can see that this is true by executing the followig query

```
SELECT 'x' FROM DUAL WHERE '' IS NULL

```

This should return a single row, meaning that the condition `'' IS NULL` is `true`.