时间:2021-05-23
类型:
1.普通游标 只有NEXT操作
2.滚动游标 有多种操作
1.普通游标
DECLARE @username varchar(20),@UserId varchar(100)DECLARE cursor_name CURSOR FOR --定义游标 SELECT TOP 10 UserId,UserName FROM UserInfo ORDER BY UserId DESCOPEN cursor_name --打开游标FETCH NEXT FROM cursor_name INTO @UserId,@username --抓取下一行游标数据WHILE @@FETCH_STATUS = 0 BEGIN PRINT '用户ID:'+@UserId+' '+'用户名:'+@username FETCH NEXT FROM cursor_name INTO @UserId,@username ENDCLOSE cursor_name --关闭游标DEALLOCATE cursor_name --释放游标结果:
用户ID:zhizhi 用户名:邓鸿芝
用户ID:yuyu 用户名:魏雨
用户ID:yujie 用户名:李玉杰
用户ID:yuanyuan 用户名:王梦缘
用户ID:YOUYOU 用户名:lisi
用户ID:yiyiren 用户名:任毅
用户ID:yanbo 用户名:王艳波
用户ID:xuxu 用户名:陈佳绪
用户ID:xiangxiang 用户名:李庆祥
用户ID:wenwen 用户名:魏文文
2.滚动游标
--带SCROLL选项的游标SET NOCOUNT ONDECLARE C SCROLL CURSOR FOR --SCORLL 后,有了更多的游标操作(滚动游标) SELECT TOP 10 UserId,UserName FROM UserInfo ORDER BY UserId DESCOPEN C FETCH LAST FROM C --最后一行的数据,并将当前行为指定行FETCH ABSOLUTE 4 FROM C --从第一行开始的第4行数据,并将当前行为指定行 这里的n可正可负,n>0 往下翻,n<0 往上翻FETCH RELATIVE 3 FROM C --相对于当前行的后3行数据,并将当前行为指定行 这里的n可正可负FETCH RELATIVE -2 FROM C --相对于当前行的前2行数据,并将当前行为指定行FETCH PRIOR FROM C ----相对于当前行的前1行数据FETCH FIRST FROM C --刚开始第一行的数据,并将当前行为指定行FETCH NEXT FROM C --相对于当前行的后1行数据CLOSE CDEALLOCATE C结果(可以参考第一个结果分析):
具体FETCH用法:
FETCH [ [ NEXT | PRIOR | FIRST | LAST | ABSOLUTE { n | @nvar } | RELATIVE { n | @nvar } ] FROM ] { { [ GLOBAL ] cursor_name } | @cursor_variable_name } [ INTO @variable_name [ ,...n ] ]Arguments
NEXT
Returns the result row immediately following the current row and increments the current row to the row returned. If FETCH NEXT is the first fetch against a cursor, it returns the first row in the result set. NEXT is the default cursor fetch option.
PRIOR
Returns the result row immediately preceding the current row, and decrements the current row to the row returned. If FETCH PRIOR is the first fetch against a cursor, no row is returned and the cursor is left positioned before the first row.
FIRST
Returns the first row in the cursor and makes it the current row.
LAST
Returns the last row in the cursor and makes it the current row.
ABSOLUTE { n| @nvar}
If n or @nvar is positive, returns the row n rows from the front of the cursor and makes the returned row the new current row. If n or @nvar is negative, returns the row n rows before the end of the cursor and makes the returned row the new current row. If n or @nvar is 0, no rows are returned. n must be an integer constant and @nvar must be smallint, tinyint, or int.
RELATIVE { n| @nvar}
If n or @nvar is positive, returns the row n rows beyond the current row and makes the returned row the new current row. If n or @nvar is negative, returns the row n rows prior to the current row and makes the returned row the new current row. If n or @nvar is 0, returns the current row. If FETCH RELATIVE is specified with n or @nvar set to negative numbers or 0 on the first fetch done against a cursor, no rows are returned. n must be an integer constant and @nvar must be smallint, tinyint, or int.
GLOBAL
Specifies that cursor_name refers to a global cursor.
cursor_name
Is the name of the open cursor from which the fetch should be made. If both a global and a local cursor exist with cursor_name as their name, cursor_name to the global cursor if GLOBAL is specified and to the local cursor if GLOBAL is not specified.
@cursor_variable_name
Is the name of a cursor variable referencing the open cursor from which the fetch should be made.
INTO @variable_name[ ,...n]
Allows data from the columns of a fetch to be placed into local variables. Each variable in the list, from left to right, is associated with the corresponding column in the cursor result set. The data type of each variable must either match or be a supported implicit conversion of the data type of the corresponding result set column. The number of variables must match the number of columns in the cursor select list.
以上就是详解SQL游标的用法的详细内容,更多关于SQL游标用法的资料请关注其它相关文章!
声明:本页内容来源网络,仅供用户参考;我单位不保证亦不表示资料全面及准确无误,也不保证亦不表示这些资料为最新信息,如因任何原因,本网内容或者用户因倚赖本网内容造成任何损失或损害,我单位将不会负任何法律责任。如涉及版权问题,请提交至online#300.cn邮箱联系删除。
本文实例讲述了MySQL游标概念与用法。分享给大家供大家参考,具体如下:1、游标的概念(Cursor)一条sql,对应N条资源,取出资源的接口,就是游标,沿着游
Oracle中的游标和函数详解1.游标游标是一种PL/SQL控制结构;可以对SQL语句的处理进行显示控制,便于对表的行数据逐条进行处理。游标并不是一个数据库对象
本文实例讲述了mysql游标的原理与用法。分享给大家供大家参考,具体如下:本文内容:什么是游标创建游标使用游标首发日期:2018-04-18什么是游标:如果你前
下面看下Oracle游标的简易用法,具体代码如下所示:createorreplaceprocedureNW_DelYW(iOPERATION_IDnumber,
本文实例讲述了Oracle存储过程游标用法。分享给大家供大家参考,具体如下:使用游标的5个步骤1、声明一些变量用于保存select语句返回的指2、声明游标,并指