当前位置:Gxlcms > mysql > ORA-06531:Referencetouninitializedcollection问题解决

ORA-06531:Referencetouninitializedcollection问题解决

时间:2021-07-01 10:21:17 帮助过:30人阅读

ORA-06531:Reference to uninitialized collection 问题解决


错误信息:

ORA-06531:Reference to uninitialized collection

错误SQL代码:

declare  
  TYPE t_student_var IS TABLE OF VARCHAR2(100);
  
  v_tbl_name t_student_var;
begin
  select name into v_tbl_name(1) from t_student where gid = 1;
  select name into v_tbl_name(2) from t_student where gid = 2;
  select name into v_tbl_name(3) from t_student where gid = 3;
  dbms_output.put_line(v_tbl_name(1));
  dbms_output.put_line(v_tbl_name(2));
  dbms_output.put_line(v_tbl_name(3));
end;

问题分析:

Oracle自定义类型语法:

TYPE type_name IS TABLE OF element_type INDEX BY [BINARY_INTEGER | PLS_INTEGER | VARRAY2]; 其中:INDEX BY: 该语句的作用是使Number类型的下标自增长,,自动初始化,并分配空间,有了该语句,向表记录插入元素时,不需要显示初始化,也不需要通过extend分配空间。Binary_Integer 与 Pls_Integer 都是整型类型.

Binary_Integer类型变量值计算是由Oracle来执行,不会出现溢出,但是执行速度较慢,因为它是由Oracle模拟执行。而Pls_Integer的执行是由硬件即直接由CPU来运算,因而会出现溢出,但其执行速度较前者快许多。

通过上面的说明可以知道解决的办法有两个:

1、定义记录表类型时,要加上INDEX BY语句,修改之后如下:

declare  
  TYPE t_student_var IS TABLE OF VARCHAR2(100) INDEX BY BINARY_INTEGER;
  
  v_tbl_name t_student_var;
begin
  select name into v_tbl_name(1) from t_student where gid = 1;
  select name into v_tbl_name(2) from t_student where gid = 2;
  select name into v_tbl_name(3) from t_student where gid = 3;
  dbms_output.put_line(v_tbl_name(1));
  dbms_output.put_line(v_tbl_name(2));
  dbms_output.put_line(v_tbl_name(3));
end;

这种方式比较简易,建议使用这种方式.

2、初始化,并使用extend语句扩展空间,修改之后如下:

declare  
  TYPE t_student_var IS TABLE OF VARCHAR2(100);
  
  v_tbl_name t_student_var := t_student_var();--初始化
begin
  v_tbl_name.extend;--扩展空间
  select name into v_tbl_name(1) from t_student where gid = 1;
  v_tbl_name.extend;--扩展空间
  select name into v_tbl_name(2) from t_student where gid = 2;
  v_tbl_name.extend;--扩展空间
  select name into v_tbl_name(3) from t_student where gid = 3;
  dbms_output.put_line(v_tbl_name(1));
  dbms_output.put_line(v_tbl_name(2));
  dbms_output.put_line(v_tbl_name(3));
end;

另外,使用extend(n),一次性扩展n个空间,所以下面代码和上面的效果是一样的:

declare  
  TYPE t_student_var IS TABLE OF VARCHAR2(100);
  
  v_tbl_name t_student_var := t_student_var();--初始化
begin
  v_tbl_name.extend(3);--扩展3个空间
  select name into v_tbl_name(1) from t_student where gid = 1;
  select name into v_tbl_name(2) from t_student where gid = 2;
  select name into v_tbl_name(3) from t_student where gid = 3;
  dbms_output.put_line(v_tbl_name(1));
  dbms_output.put_line(v_tbl_name(2));
  dbms_output.put_line(v_tbl_name(3));
end

以上就是ORA-06531:Reference to uninitialized collection 问题解决的内容,更多相关内容请关注PHP中文网(www.gxlcms.com)!

人气教程排行