Question

I want to add a named constraint in my CREATE TABLE statement that will cause of my columns to default to the system date. I know how to define a primary key constraint:

constraint cust_ID_PK PRIMARY KEY (Cust_ID)

How do I define a constraint on Hire_Date that defaults it to the system date?

Answer 1

You can set a default for a column. But that is not a constraint so you cannot name it.

CREATE TABLE customer (
  cust_id   NUMBER,
  hire_date DATE DEFAULT sysdate,
  CONSTRAINT cust_id_pk PRIMARY KEY( cust_id )
)

A default is not a type of constraint so you can’t use the syntax for defining a constraint to define a default. A default is not an object type in the database so it cannot have a name. A default is a property of a column– it can only be declared inline with the column.