Oracle PL/SQL Programming: A Developer's Workbook

Intermediate

17-6.	When you want to call a packaged function (a function defined in the specification of a package) from within an SQL statement, what statement do you need to add to that specification? What is it for?
17-7.	What are the four different purity levels you can attempt to assert about a function?
17-8.	Add the necessary code to this package specification to assert all four purity levels for the total function: CREATE OR REPLACE PACKAGE comp IS FUNCTION total (sal_in IN NUMBER, comm_in IN NUMBER := NULL) RETURN NUMBER; END; /
17-9.	What is the minimum required purity level for a packaged function to be callable inside SQL?
17-10.	Under what circumstances do you need to assert the WNPS purity level for a packaged function or procedure?
17-11.	Which purity levels can you assert about the following function if you define it inside a package? FUNCTION betwnstr (str IN VARCHAR2, startat IN INTEGER, endat IN INTEGER := NULL) RETURN VARCHAR2 IS BEGIN RETURN SUBSTR (str, startat, endat-startat+1); END;
17-12.	Which purity levels can you assert about the following function? FUNCTION ename_from (empno_in IN emp.empno%TYPE) RETURN emp.ename%TYPE IS retval emp.ename%TYPE; BEGIN SELECT ename INTO retval FROM emp WHERE empno = empno_in; RETURN retval; END;
17-13.	Suppose that you define the following package in the database: PACKAGE who_is_paying_whom IS too_low CONSTANT NUMBER := 15000; /* This is above minimum wage! */ my_salary CONSTANT NUMBER := too_low; ceo_salary NUMBER := too_low * 250; END; ...