Default value
A default value can be defined for a column. When you add a new row to myTable but don't specify the values for the column with default value, those columns are set to the default values.
The following table has a VARCHAR2 with default value set to N/A.
SQL> CREATE TABLE myTable (
2 id INTEGER CONSTRAINT default_pk PRIMARY KEY,
3 status VARCHAR2(20) DEFAULT 'N/A' NOT NULL
4 );
Table created.
SQL>
SQL> INSERT INTO myTable(id) VALUES (1);
1 row created.
SQL> select * from myTable;
ID STATUS
---------- --------------------
1 N/A
SQL>
The following table has a Date type column with SYSDATE default value
SQL> CREATE TABLE myTable (
2 id INTEGER CONSTRAINT default_pk PRIMARY KEY,
3 last_modified DATE DEFAULT SYSDATE
4 );
Table created.
SQL>
SQL> INSERT INTO myTable(id) VALUES (1);
1 row created.
SQL> select * from myTable;
ID LAST_MODI
---------- ---------
1 06-JUL-11
SQL>