How to make Not null field to Null

[manutektips]

Hi,
I have a field in a table which is NOT NULL now and the table has data. I tried to Alter the table to make this field NULL, but could not. Can anyone suggest a way to acheive this?

 

[Dagon]

Did you get any sort of error message when you tried to do the alter table command ?

 

[manutektips]

Yes, The error message is : ORA-01451: column to be modified to NULL cannot be modified to NULL

 

[Dagon]

/ *Cause: the column may already allow NULL values, the NOT NULL constraint
// is part of a primary key or check constraint.
// *Action: if a primary key or check constraint is enforcing the NOT NULL
// constraint, then drop that constraint.

If it is part of the primary key, you cannot modify it.