I don't want to stop the production and then empty the table then run above query.I want to run this query in production...to do Not Null condition as yes

Hi,

If I update a table as:

ALTER TABLE T008F002E20001 ALTER COLUMN K1 char(10) NOT NULL;

and that colum has null values but I don't want to stop the production and then empty the table then run above query.I want to run this query in production...to do Not Null condition as  yes.

Can I do it..the rows are around 200345675 in the table.

Thanks