long类型字段转换成varchar2类型

參考文档： How to Convert a Long to Varchar2 (文档 ID 228532.1)
/*long类型字段转换成varchar2类型*/
--建表
create table dxmy_long(lon long,var varchar2(100 ));
--插数
insert into dxmy_long values( '丹心','明月' );
commit;
--查看
declare
       v1 varchar2(100 );
begin
   select lon into v1 from dxmy_long;
   dbms_output.put_line(v1);
end;

丹心
--将lon数据存到var中
declare
       v1 varchar2(100 );
begin
   select lon into v1 from dxmy_long;
   dbms_output.put_line(v1);
   update dxmy_long set var = v1;
   commit;
end;
--查证
select * from dxmy_long;
 
LON                                                                              VAR
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
丹心                                                                             丹心
--假设有多行须要转换
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
insert into dxmy_long values( '丹心','明月' );
commit;

declare
   v1 varchar2( 100);
   CURSOR c_Select IS select lon from dxmy_long;
begin
   Open c_Select;
   LOOP
      Fetch c_Select into v1;
      Exit when c_Select%NOTFOUND;
      update dxmy_long set var = v1;
   END LOOP;
   commit;
   Close c_Select;
END;

--查证
SQL> select * from dxmy_long;
 
LON                                                                              VAR
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
丹心                                                                             丹心
 
10 rows selected