Change the default value of column NOT NULL to NULL

Hi all
How can I change the default value of column not NULL to NULL?
Suppose I have run the following commands:
SQL> alter table hr.test modify temp_num2 default null;

Table altered.

SQL> desc hr.test;
 Name                            Null?    Type
 ----------------------------------------- -------- ----------------------------
 TEMP_NUM                             NUMBER
 TEMP_NUM2                       NOT NULL NUMBER
Why forced temp_num2 has not changed with the NULL value? I'm under 11.g rel2

Best regards
Valerie

You can NOT change the column constraint NULL to contain NULL values by:

alter table table_name modify column_name null; 

After this change, the column can contain null values. In Oracle, not null constraints are created automatically when not null is specified for a column. Similarly, they are deleted automatically when the column is changed to allow NULL values.

Tags: Database

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