游标中做更新操作的两种用法

--游标中做更新操作的两种用法
--表结构
Create Table agentmgr.yangbc_test1(Id Number(6), Name Varchar2(64));
Select t.*,Rowid From agentmgr.yangbc_test1 t;

--1:
/*在你取完部分数据并执行的过程中，可能有commit或者rollback语句，导致在表t上加的lock被释放掉，
再取数据的时候导致出错。*/
declare
cursor hh is select Name from yangbc_test1 for update;
v_Name Varchar2(64):='';
begin
open hh;
loop
fetch hh into v_Name;
exit when hh%notfound;
update yangbc_test1 set Id='18' where current of hh;
--commit; -- releases locks,去掉就可以了
dbms_output.put_line('v_Name='||v_Name);
end loop;
Commit;--在这里提交
close hh;
end;

--2:
/*If you want to fetch across commits, do not use the FOR UPDATE and CURRENT OF
clauses. Instead, use the ROWID pseudocolumn to mimic the CURRENT OF clause.
Simply select the rowid of each row into a UROWID variable. Then, use the rowid to
identify the current row during subsequent updates and deletes. An example
follows:*/
declare
cursor hh is select Name,Rowid from yangbc_test1;
v_Name Varchar2(64):='';
v_rowid UROWID;
begin
open hh;
loop
fetch hh into v_Name,v_rowid;
exit when hh%notfound;
update yangbc_test1 set Id='17' Where Rowid=v_rowid;
commit; -- releases locks
dbms_output.put_line('v_Name='||v_Name);
end loop;
close hh;
end;