http://www.itpub.net/thread-1499223-9-1.html89楼 我创建了如下包头：
CREATE OR REPLACE PACKAGE plch_pkg AUTHID DEFINER IS TYPE names_t IS TABLE OF VARCHAR2 (20) INDEX BY PLS_INTEGER; END plch_pkg; /
哪些选项在执行之后会显示"3"? (A)
DECLARE
l_names CONSTANT plch_pkg.names_t
:= plch_pkg.names_t ('Horton', 'Hears', 'A Who') ;
BEGIN
DBMS_OUTPUT.put_line (l_names.COUNT);
END;
/
SQL> DECLARE
2 l_names CONSTANT plch_pkg.names_t
3 := plch_pkg.names_t ('Horton', 'Hears', 'A Who') ;
4 BEGIN
5 DBMS_OUTPUT.put_line (l_names.COUNT);
6 END;
7 /
DECLARE
l_names CONSTANT plch_pkg.names_t
:= plch_pkg.names_t ('Horton', 'Hears', 'A Who') ;
BEGIN
DBMS_OUTPUT.put_line (l_names.COUNT);
END;
ORA-06550: 第 3 行, 第 10 列:
PLS-00222: 在此范围中不存在名为 'NAMES_T' 的函数
ORA-06550: 第 2 行, 第 14 列:
PL/SQL: Item ignored
ORA-06550: 第 5 行, 第 26 列:
PLS-00320: 此表达式的类型声明不完整或格式不正确
ORA-06550: 第 5 行, 第 4 列:
PL/SQL: Statement ignored
SQL>
(B)
DECLARE l_names CONSTANT plch_pkg.names_t := plch_pkg.names_t () ; BEGIN l_names (1) := 'Horton'; l_names (2) := 'Hears'; l_names (3) := 'A Who'; DBMS_OUTPUT.put_line (l_names.COUNT); END; /
SQL> DECLARE 2 l_names CONSTANT plch_pkg.names_t 3 := plch_pkg.names_t () ; 4 BEGIN 5 l_names (1) := 'Horton'; 6 l_names (2) := 'Hears'; 7 l_names (3) := 'A Who'; 8 DBMS_OUTPUT.put_line (l_names.COUNT); 9 END; 10 / DECLARE l_names CONSTANT plch_pkg.names_t := plch_pkg.names_t () ; BEGIN l_names (1) := 'Horton'; l_names (2) := 'Hears'; l_names (3) := 'A Who'; DBMS_OUTPUT.put_line (l_names.COUNT); END; ORA-06550: 第 3 行, 第 29 列: PLS-00222: 在此范围中不存在名为 'NAMES_T' 的函数 ORA-06550: 第 2 行, 第 14 列: PL/SQL: Item ignored ORA-06550: 第 5 行, 第 4 列: PLS-00320: 此表达式的类型声明不完整或格式不正确 ORA-06550: 第 5 行, 第 4 列: PL/SQL: Statement ignored ORA-06550: 第 6 行, 第 4 列: PLS-00320: 此表达式的类型声明不完整或格式不正确 ORA-06550: 第 6 行, 第 4 列: PL/SQL: Statement ignored ORA-06550: 第 7 行, 第 4 列: PLS-00320: 此表达式的类型声明不完整或格式不正确 ORA-06550: 第 7 行, 第 4 列: PL/SQL: Statement ignored ORA-06550: 第 8 行, 第 26 列: PLS-00320: 此表达式的类型声明不完整或格式不正确 ORA-06550: 第 8 行, 第 4 列: PL/SQL: Statement ignored SQL>
(C)
CREATE OR REPLACE FUNCTION plch_dr_seuss_names RETURN plch_pkg.names_t IS l_return plch_pkg.names_t; BEGIN l_return (1) := 'Horton'; l_return (2) := 'Hears'; l_return (3) := 'A Who'; RETURN l_return; END plch_dr_seuss_names; / DECLARE l_names CONSTANT plch_pkg.names_t := plch_dr_seuss_names () ; BEGIN DBMS_OUTPUT.put_line (l_names.COUNT); END; /
SQL> CREATE OR REPLACE FUNCTION plch_dr_seuss_names 2 RETURN plch_pkg.names_t 3 IS 4 l_return plch_pkg.names_t; 5 BEGIN 6 l_return (1) := 'Horton'; 7 l_return (2) := 'Hears'; 8 l_return (3) := 'A Who'; 9 RETURN l_return; 10 END plch_dr_seuss_names; 11 / Function created SQL> DECLARE 2 l_names CONSTANT plch_pkg.names_t 3 := plch_dr_seuss_names () ; 4 BEGIN 5 DBMS_OUTPUT.put_line (l_names.COUNT); 6 END; 7 / 3 PL/SQL procedure successfully completed SQL>
(D)
CREATE OR REPLACE FUNCTION plch_dr_seuss_names (
name1_in IN VARCHAR2
, name2_in IN VARCHAR2
, name3_in IN VARCHAR2)
RETURN plch_pkg.names_t
IS
l_return plch_pkg.names_t;
BEGIN
l_return (1) := name1_in;
l_return (2) := name2_in;
l_return (3) := name3_in;
RETURN l_return;
END plch_dr_seuss_names;
/
DECLARE
l_names CONSTANT plch_pkg.names_t
:= plch_dr_seuss_names ('Horton', 'Hears', 'A Who') ;
BEGIN
DBMS_OUTPUT.put_line (l_names.COUNT);
END;
/
SQL> CREATE OR REPLACE FUNCTION plch_dr_seuss_names (
2 name1_in IN VARCHAR2
3 , name2_in IN VARCHAR2
4 , name3_in IN VARCHAR2)
5 RETURN plch_pkg.names_t
6 IS
7 l_return plch_pkg.names_t;
8 BEGIN
9 l_return (1) := name1_in;
10 l_return (2) := name2_in;
11 l_return (3) := name3_in;
12 RETURN l_return;
13 END plch_dr_seuss_names;
14 /
Function created
SQL> DECLARE
2 l_names CONSTANT plch_pkg.names_t
3 := plch_dr_seuss_names ('Horton', 'Hears', 'A Who') ;
4 BEGIN
5 DBMS_OUTPUT.put_line (l_names.COUNT);
6 END;
7 /
3
PL/SQL procedure successfully completed
SQL>
答案CD 答案说明93楼
2011-10-27 答案CD. ORACLE只对嵌套表(NESTED TABLE)和可变数组(VARRAY)提供构造函数(constructor function), ASSOCIATED ARRAY (即INDEX BY表)则没有这个构造函数，必须采用自定义函数。常量在声明的部分必须赋值，不能够在块中赋值。
