Microsoft SQL Server 基本仅前进光标
示例
通常，您会希望避免使用游标，因为它们会对性能产生负面影响。但是，在某些特殊情况下，您可能需要逐条记录遍历数据记录并执行一些操作。
DECLARE @orderId AS INT
-- here we are creating our cursor, as a local cursor and only allowing
-- forward operations
DECLARE rowCursor CURSOR LOCAL FAST_FORWARD FOR
-- this is the query that we want to loop through record by record
SELECT [OrderId]
FROM [dbo].[Orders]
-- first we need to open the cursor
OPEN rowCursor
-- now we will initialize the cursor by pulling the first row of data, in this example the [OrderId] column,
-- and storing the value into a variable called @orderId
FETCH NEXT FROM rowCursor INTO @orderId
-- start our loop and keep going until we have no more records to loop through
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT @orderId
-- this is important, as it tells SQL Server to get the next record and store the [OrderId] column value into the @orderId variable
FETCH NEXT FROM rowCursor INTO @orderId
END
-- this will release any memory used by the cursor
CLOSE rowCursor
DEALLOCATE rowCursor
热门推荐
10 喜得孙子祝福语简短唯美
11 婚礼祝福语简短朴实大众
12 员工周年祝福语大全简短
13 家长回复节日祝福语简短
14 简短生日祝福语老同学
15 夜雨祝福语简短10字
16 蛋糕祝福语简短闺蜜
17 部门过年祝福语简短独特
18 简短精炼的结婚祝福语