Adding a Constraint : Constraint « Table « Oracle PL/SQL Tutorial

Constraint	Constraint Type	Meaning
CHECK	C	Specifies a certain condition for a column, or group of columns.
NOT NULL	C	Not null column
PRIMARY KEY	P	primary key
FOREIGN KEY	R	foreign key
UNIQUE	U	unique
CHECK OPTION	V	Specifies that DML operations on a view must satisfy the subquery.
READ ONLY	O	Specifies that a view may only be read from.

SQL> CREATE TABLE pet (
  2  id NUMBER(38) CONSTRAINT pk_pet PRIMARY KEY NOT NULL
  3  );

Table created.

SQL>
SQL>
SQL>
SQL> drop table pet;

Table dropped.

SQL>
SQL>

6.10.Constraint
	6.10.1.	Adding a Constraint
	6.10.2.	Add constaint for a date type column: larger than a certain date
	6.10.3.	Adding a 'NOT NULL' Constraint
	6.10.4.	The database automatically assigns a name to the constraint
	6.10.5.	Dropping a Constraint
	6.10.6.	Disabling a Constraint
	6.10.7.	Add CASCADE to the end of a DISABLE CONSTRAINT clause
	6.10.8.	Enabling a Constraint
	6.10.9.	You can also choose to apply a constraint to new data only by specifying ENABLE NOVALIDATE.
	6.10.10.	Deferred Constraints
	6.10.11.	How to drop a constaint
	6.10.12.	Violate a constraint
	6.10.13.	Cascade constraints