title: MODIFY or ADD to add NOT NULL constraint to a column? Oracle sql
body: <p>ORDERS table in the Oracle Database:</p>
  
  <pre><code>ORDERS
  ORDER_ID NOT NULL NUMBER(4)
  ORDATE_DATE DATE
  CUSTOMER_ID NUMBER(3)
  ORDER_TOTAL NUMBER(7,2)
  </code></pre>
  
  <p>The ORDERS table contains data and all orders have been assigned a customer ID. I'm trying to add a NOT NULL constraint to the CUSTOMER_ID column. Would I use MODIFY CONSTRAINT or ADD CONSTRAINT? I was told you have to drop the constraint and ADD the new one, but if there is no existing constraint to Customer ID number, would it be MODIFY?</p>