基于游标的定位DELETE/UPDATE语句

2023-06-14,,

如果游标是可更新的(也就是说,在定义游标语句中不包括Read Only 参数),就可以用游标从游标数据的源表中DELETE/UPDATE行,即DELETE/UPDATE基于游标指针的当前位置的操作;
举例:
--删除当前行的记录
Declare cur_Depart Cursor
For Select cDeptID,cDeptName From Department into @DeptID,@DeptName
Open cur_Depart
Fetch From cur_Depart into @DeptID,@DeptName
Delete From Department Where CURRENT OF cur_Depart
--更新当前行的内容
Declare cur_Depart Cursor
For Select cDeptID,cDeptName From Department into @DeptID,@DeptName
Open cur_Depart
Fetch From cur_Depart into @DeptID,@DeptName
Update Department Set cDeptID='2007' + @DeptID Where CURRENT OF cur_Depart
 
一个Update例子

create table t1
(
id int
) --插入数据,这里插入奇数
declare @i int
select @i = 0
while (@i < 100)
begin
insert into t1 select @i * 2 +1
select @i = @i + 1
end --游标处理
declare @ii int
declare @k int
select @k = 1,@ii = 1 declare c_update_id cursor for
select id from t1
for update open c_update_id fetch next from c_update_id into @ii
while(@@fetch_status=0)
begin
update t1 set id = @k where current of c_update_id fetch next from c_update_id into @ii
select @k = @k + 1
end CLOSE c_update_id
DEALLOCATE c_update_id --查询
select * from t1 --删除环境
drop table t1

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