Oracle PL/SQL Programming: A Developer's Workbook

Expert

Q:
3-16.	No. The IF statement is the only native PL/SQL conditional syntax.
Q:
3-17.	There are two basic possibilities: Use the SQL DECODE function inside a SELECT FROM dual (or other table with just one row). Here is a demonstration of the DECODE solution: eypBEGIN SELECT DECODE (friend_type, 'B', 'BEST', 'K', 'BACKSTABBING', 'C', 'CLOSE', 'L', 'LIKE A BROTHER', 'ACQUAINTANCE') INTO friend_descrip FROM dual; Structure the IF statement to look and act as much like a CASE statement as possible. Here is an example of an IF statement posing as a CASE statement: BEGIN IF friend_type = 'B' THEN friend_descrip = 'BEST' ; ELSIF friend_type = 'K' THEN friend_descrip = 'BACKSTABBING' ; ELSIF friend_type = 'C' THEN friend_descrip = 'CLOSE' ; ELSIF friend_type = 'L' THEN friend_descrip = 'LIKE A BROTHER'; ; ELSE 'ACQUAINTANCE'; END IF;
Q:
3-18.	Here is a function that implements an inline IF-ELSE statement, returning one of two strings: CREATE OR REPLACE FUNCTION ifelse (bool_in IN BOOLEAN, tval_in IN VARCHAR2, fval_in IN VARCHAR2) RETURN VARCHAR2 IS BEGIN IF bool_in THEN RETURN tval_in; ELSE RETURN fval_in; END IF; END; / And here is an example of the ifelse function put to use: BEGIN emp_status := ifelse ( hiredate > ADD_MONTHS (SYSDATE, -216), 'TOO YOUNG', 'OLD ENOUGH'); This example is equivalent to this code: BEGIN IF hiredate > ADD_MONTHS (SYSDATE, -216) THEN emp_status := 'TOO YOUNG'; ELSE emp_status := 'OLD ENOUGH'; END IF; If you like this technique (it comes in especially handy when you want ...