在以下程序中有一个我无法找到的逻辑错误,你能找到它是什么吗?以下过程导致以下错误:
ora-01001无效游标01001
这是程序:
CREATE OR REPLACE PROCEDURE P_C is
   v_tab_name varchar2(40);
  -- v_col_name varchar2(100);
   var1 varchar2(2000);
   var2 varchar2(2000);
   tab_var varchar2(2000);
   /* First cursor */
   CURSOR get_tables IS
     SELECT  tab.table_name
     FROM user_tables tab;
   /* Second cursor */
   CURSOR get_columns IS
     SELECT DISTINCT cols.column_name
     FROM user_tab_cols cols
     WHERE cols.table_name = v_tab_name;
   BEGIN
var1 := null;
   -- Open first cursor
for gettab in get_tables
   LOOP
tab_var :=gettab.table_name;
      -- Open second cursor
for getcols in get_columns
      LOOP
if var1 is null then
var1 :=getcols.column_name;
else
var1 := var1 ||','|| getcols.column_name;
end if;
 END LOOP;
      CLOSE get_columns;
   END LOOP;
   CLOSE get_tables;
EXCEPTION
   WHEN OTHERS THEN
      raise_application_error(-20001,'An error was encountered - '||SQLCODE||' -ERROR- '||SQLERRM);
end P_C;
解决方法
 检查以下代码,这将工作.主要的是,使用游标变量.所以代码将更清晰,更容易.
 
但请考虑一下,您将获得所有表的所有列.好多啊! 
CREATE OR REPLACE PROCEDURE P_C is
  var1    varchar2(32000);
  /* First cursor */
  CURSOR get_tables IS
    SELECT tab.table_name FROM user_tables tab;
  /* Second cursor */
  CURSOR get_columns (ci_tab_name in varchar2) IS
    SELECT DISTINCT cols.column_name
      FROM user_tab_cols cols
     WHERE cols.table_name = ci_tab_name;
BEGIN
  var1 := null;
  for c1 in get_tables loop
    for c2 in get_columns (c1.table_name) loop
      if var1 is not null then
        var1 := var1 || ',';
      end if;
      var1 := var1 || c2.column_name;
    end loop;
  end loop;
EXCEPTION
  WHEN OTHERS THEN
    raise_application_error(-20001,'An error was encountered - ' || SQLCODE ||
                            ' -ERROR- ' || SQLERRM);
end P_C;