SYBASE中的游标的替代方法？

Question

假设我正在处理10张图书卡，每张卡片都有客户价值（例如会员编号，会员姓名......），我需要为每张卡片更新一个值。

如果我想从数据库中抓取所有十个，但只想每次更新一行，是否有光标的替代？我知道一个while循环可能会工作，但是如何才能在每次循环时抓取一行，直到完成所有10张卡？

Answer 1

不需要使用游标。我大部分时间都在使用它：

declare @uid int -- this is the type unique index on the table you're updating 

-- Copy out the unique ids of the rows you want to update to a temporary table 
select uid into #temp from customers -- you can use a where condition here 

-- Loop through the rows of the temp table 
while exists (select 1 from #temp) 
begin 
    set rowcount 1 
    select @uid = uid from #temp -- pull one uid from the temp table 
    set rowcount 0 
    delete from #temp where uid = @uid -- delete that uid from the temp table 

    -- Do something with the uid you have 
    update customers set name = 'Joe Shmoe' where uid = @uid 

end 

Answer 2

可以使用特定列上的聚簇索引在表上循环。由于聚集索引按排序顺序排列行，因此它可以像循环的索引变量一样使用。

declare @uid int 
select @uid = 0 -- assume the uids in table are > 0 
declare @rowsaf int 
select @rowsaf = 1 

while @rowsaf > 1 
begin 
    set rowcount 1 
    select @uid = uid from customers where uid > @uid 
    select @rowsaf = @@rowcount 

    -- update the row using @uid 
end 

set rowcount 0 

Here is the article对此有详细解释。