IMPACT OF CHANGING REFERENCED OBJECT ON FUNCTIONS
If we add any column to the table which is used in a stored function then the function get invalidated. But Oracle automatically compiled the invalid object when it is called for execution.
CREATE OR REPLACE FUNCTION GET_EMP_NAME(P_EMPLOYEE_ID NUMBER)
RETURN VARCHAR2
IS
V_EMP_NAME VARCHAR2(100);
BEGIN
SELECT FIRST_NAME||' '||LAST_NAME
INTO V_EMP_NAME
FROM EMPLOYEES_COPY
WHERE EMPLOYEE_ID = P_EMPLOYEE_ID;
--
RETURN V_EMP_NAME;
EXCEPTION
WHEN OTHERS THEN
V_EMP_NAME := 'EMPLOYEE DOES NOT EXISTS';
RETURN V_EMP_NAME;
END;
/
SELECT *
FROM USER_OBJECTS
WHERE OBJECT_NAME IN ('EMPLOYEES_COPY', 'GET_EMP_NAME');
Now adding new column in the table EMPLOYEES_COPY.
ALTER TABLE EMPLOYEES_COPY ADD (FULL_NAME VARCHAR2(100));
SELECT *
FROM USER_OBJECTS
WHERE OBJECT_NAME IN ('EMPLOYEES_COPY', 'GET_EMP_NAME');
Now if we invoke the function through a SQL query then Oracle will automatically compile the function.
SELECT GET_EMP_NAME(100) FROM DUAL;
Now if we check the status of the function then it will show VALID.
SELECT *
FROM USER_OBJECTS
WHERE OBJECT_NAME IN ('EMPLOYEES_COPY', 'GET_EMP_NAME');
Now if we change the definition of LAST_NAME column to see the impact on function GET_EMP_NAME.
DESC EMPLOYEES_COPY;
ALTER TABLE EMPLOYEES_COPY MODIFY (LAST_NAME VARCHAR2(120));
SELECT *
FROM USER_OBJECTS
WHERE OBJECT_NAME IN ('EMPLOYEES_COPY', 'GET_EMP_NAME');
SELECT GET_EMP_NAME(100) FROM DUAL;
SELECT *
FROM USER_OBJECTS
WHERE OBJECT_NAME IN ('EMPLOYEES_COPY', 'GET_EMP_NAME');
So we can conclude that any change in referenced table will make the stored function invalidated. But once try to we execute the function it will automatically be compiled by Oracle.
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