oracle apex sql alter table constraint foreign key

ORA-02291: integrity constraint (TEST.EMP_ADD_FK) violated - parent key not found SQL> insert into EMPLOYEE_ADDRESS values('abcd efgh',8) Now while entering the data in EMPLOYEE_ADDRESS table the data should be already present in EMPLOYEE table.Otherwise foreign key violation will result. SQL> insert into EMPLOYEE_ADDRESS values('abcd efgh',1) Now let us add address for this particular employee in EMPLOYEE_ADDRESS table. SQL> insert into EMPLOYEE values('ABCD',1,12345) Now let us insert one record in EMPLOYEE table. SQL> create table EMPLOYEE_ADDRESS(address varchar2(200),emp_id number,CONSTRAINT EMP_ADD_FK FOREIGN KEY (emp_id) REFERENCES EMPLOYEE(emp_id)) Now create an Employee address table which holds the address details of the employees.The address table is linked to EMPLOYEE table through the foreign key emp_id SQL> create table EMPLOYEE(name VARCHAR2(50),emp_id NUMBER,salary NUMBER(8,2), CONSTRAINT EMPLOYEE_ID_PK PRIMARY KEY (emp_id)) Let us create an EMPLOYEE table which holds the employee information like name ,id and salary.

Usage Create table statement with foreign key constraint will create table with referential integrity.įoreign Key holds the reference to another table column value.It is also known as references constraint.Ī foreign key means that values in one table must also appear in another table.A references constraint is only applied at SQL ‘insert’ and ‘delete’ times.Ī foreign key can be defined in either a CREATE TABLE statement or an ALTER TABLE statement. 0 Flares Twitter 0 Facebook 0 Google+ 0 LinkedIn 0 Buffer 0 Email - Filament.io 0 Flares ×

Oracle apex sql alter table constraint foreign key