Oracle9i笔记1(22)

END;

CURSOR with Subqueries

例：

DECLARE

CURSOR my_cursor IS

SELECT * FROM DEPT D, (SELECT DEPORTNO,COUNT(*) AS STAFF FROM EMP GROUP BY DEPORTNO ) E

WHERE E.DEPORTNO=D.DEPT_NO; begin

for r_cu in my_cursor loop

DBMS_OUTPUT.PUT_LINE(r_cu.dept_name ||' : '||r_cu.staff); end loop; end;

chapter 8 Handing Exceptions

After completing this lesson, you should be able to do the following: Define PL/SQL exceptions

Recognize unhandled exceptions

List and use different types of PL/SQL exception handlers Trap unanticipated errors

Describe the effect of exception propagation in nested blocks Customize PL/SQL exception messages

Handling Exceptions with PL/SQL

An Exception is an identifier in PL/SQL that is raised during execution. How is it raised?

An Oracle error occurs. You raise it explicitly. How do you handle it? Trap it with a handler.

Propagate it to calling environment. Three types of exception

1. Predefined oracle server error

Do not declare and allow the oracle server to raise them implicitly. 2. Nonpredefined oracle server error.

Declare within the declarative section and allow the oracle server to raise them implicitly.

例：(nonpredefined) define pn =10

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