SYBASE中的遊標的替代方法？

Question

假設我正在處理10張圖書卡，每張卡片都有客戶價值（例如會員編號，會員姓名......），我需要爲每張卡片更新一個值。

如果我想從數據庫中抓取所有十個，但只想每次更新一行，是否有光標的替代？我知道一個while循環可能會工作，但是如何才能在每次循環時抓取一行，直到完成所有10張卡？

Answer 1

不需要使用遊標。我大部分時間都在使用它：

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環。由於聚集索引按排序順序排列行，因此它可以像循環的索引變量一樣使用。

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對此有詳細解釋。