A View with a CHECK OPTION Constraint

You can specify that DML statements on a view must satisfy the subquery using a CHECK OPTION constraint.

 
CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
                  ENAME VARCHAR2(10),
                  JOB VARCHAR2(9),
                  SAL NUMBER(7, 2),
                  DEPTNO NUMBER(2));

INSERT INTO EMP VALUES (1, 'SMITH', 'CLERK',     800,    20);
INSERT INTO EMP VALUES (2, 'ALLEN', 'SALESMAN', 1600,    30);
INSERT INTO EMP VALUES (3, 'WARD',  'SALESMAN', 1250,    30);
INSERT INTO EMP VALUES (4, 'JONES', 'MANAGER',  2975,    20);
INSERT INTO EMP VALUES (5, 'MARTIN','SALESMAN', 1250,    30);
INSERT INTO EMP VALUES (6, 'BLAKE', 'MANAGER',  2850,    30);
INSERT INTO EMP VALUES (7, 'CLARK', 'MANAGER',  2850,    10);
INSERT INTO EMP VALUES (8, 'SCOTT', 'ANALYST',  3000,    20);
INSERT INTO EMP VALUES (9, 'KING',  'PRESIDENT',3000,    10);
INSERT INTO EMP VALUES (10,'TURNER','SALESMAN', 1500,    30);
INSERT INTO EMP VALUES (11,'ADAMS', 'CLERK',    1500,    20);

SQL> CREATE VIEW emp_view AS
  2  SELECT *
  3  FROM emp
  4  WHERE sal < 1500
  5  WITH CHECK OPTION CONSTRAINT view_salary;

View created.

SQL>

The database would return an error because the row isn't retrievable by the view:


INSERT INTO emp_view (empno, sal) VALUES (1, 19000);
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Views:
  1. Creating and Using a View
  2. Creating and Using Simple Views
  3. Performing an INSERT Using a View
  4. A View with a CHECK OPTION Constraint
  5. View with a READ ONLY Constraint
  6. Getting Information on View Definitions with DESCRIBE command
  7. Getting Information on View Definitions with user_views view
  8. Retrieving Information on View Constraints
  9. Creating and Using Complex Views
  10. Modifying a View
  11. Alter the constraints on a view using ALTER VIEW
  12. Dropping a View
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