Deleting a row from parent table

Question

Dear Guru's
I am having two table with parent - child relationship. My problem is when I am deleting a row from parent table the curresponding child row from child table also should be deleted.
My Primary table 'Employee, EMPID Primary key
Child table 'Privilage' inthis EMPID referencing the EMPID of Employee table
My need is when I am deleting a row from parent table the curresponding child row from child table also should be deleted
I issued the SQL query like,
delete from employee where empid='12345' cascade constraints;
Then it showing me error like,
ERROR at line 1:
ORA-00933: SQL command not properly ended
Please resolve my issue , Its Top urgent
Thanks & Cheers
Antony

Answer 1

Choosing How Foreign Keys Enforce Referential Integrity
Oracle Database allows different types of referential integrity actions to be enforced, as specified with the definition of a FOREIGN KEY constraint:
Prevent Delete or Update of Parent Key The default setting prevents the deletion or update of a parent key if there is a row in the child table that references the key. For example:
CREATE TABLE Emp_tab ( 
FOREIGN KEY (Deptno) REFERENCES Dept_tab);Delete Child Rows When Parent Key Deleted The ON DELETE CASCADE action allows parent key data that is referenced from the child table to be deleted, but not updated. When data in the parent key is deleted, all rows in the child table that depend on the deleted parent key values are also deleted. To specify this referential action, include the ON DELETE CASCADE option in the definition of the FOREIGN KEY constraint. For example:
CREATE TABLE Emp_tab (
    FOREIGN KEY (Deptno) REFERENCES Dept_tab 
        ON DELETE CASCADE); Set Foreign Keys to Null When Parent Key Deleted The ON DELETE SET NULL action allows data that references the parent key to be deleted, but not updated. When referenced data in the parent key is deleted, all rows in the child table that depend on those parent key values have their foreign keys set to null. To specify this referential action, include the ON DELETE SET NULL option in the definition of the FOREIGN KEY constraint. For example:
CREATE TABLE Emp_tab (
    FOREIGN KEY (Deptno) REFERENCES Dept_tab 
        ON DELETE SET NULL);
SQL> conn scott/tiger
Connected.
SQL> create table ppk ( no number primary key);
Table created.
SQL> begin for inn in 1..10 loop insert into ppk values (inn); end loop; end;
PL/SQL procedure successfully completed.
SQL> create table ffk ( no number references ppk(no));
Table created.
SQL> begin for inn in 1..10 loop insert into ffk values (inn); end loop; end;
PL/SQL procedure successfully completed.
SQL> drop table ppk cascade constraints;
Table dropped.Message was edited by:
user52
Message was edited by:
user52
Message was edited by:
user52