域名預(yù)訂/競(jìng)價(jià)，好“米”不錯(cuò)過
這篇文章主要介紹了SQL游標(biāo)的用法，文中講解非常詳細(xì)，配合代碼幫助大家更好的理解學(xué)習(xí)，感興趣的朋友可以了解下
類型：
1.普通游標(biāo) 只有NEXT操作
2.滾動(dòng)游標(biāo) 有多種操作
1.普通游標(biāo)
DECLARE @username varchar(20),@UserId varchar(100)
DECLARE cursor_name CURSOR FOR --定義游標(biāo)
SELECT TOP 10 UserId,UserName FROM UserInfo
ORDER BY UserId DESC
OPEN cursor_name --打開游標(biāo)
FETCH NEXT FROM cursor_name INTO @UserId,@username --抓取下一行游標(biāo)數(shù)據(jù)
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT '用戶ID：'+@UserId+' '+'用戶名：'+@username
FETCH NEXT FROM cursor_name INTO @UserId,@username
END
CLOSE cursor_name --關(guān)閉游標(biāo)
DEALLOCATE cursor_name --釋放游標(biāo)
結(jié)果：
用戶ID：zhizhi 用戶名：鄧鴻芝
用戶ID：yuyu 用戶名：魏雨
用戶ID：yujie 用戶名：李玉杰
用戶ID：yuanyuan 用戶名：王夢(mèng)緣
用戶ID：YOUYOU 用戶名：lisi
用戶ID：yiyiren 用戶名：任毅
用戶ID：yanbo 用戶名：王艷波
用戶ID：xuxu 用戶名：陳佳緒
用戶ID：xiangxiang 用戶名：李慶祥
用戶ID：wenwen 用戶名：魏文文
2.滾動(dòng)游標(biāo)
--帶SCROLL選項(xiàng)的游標(biāo)
SET NOCOUNT ON
DECLARE C SCROLL CURSOR FOR --SCORLL 后，有了更多的游標(biāo)操作（滾動(dòng)游標(biāo)）
SELECT TOP 10 UserId,UserName FROM UserInfo
ORDER BY UserId DESC
OPEN C
FETCH LAST FROM C --最后一行的數(shù)據(jù)，并將當(dāng)前行為指定行
FETCH ABSOLUTE 4 FROM C --從第一行開始的第4行數(shù)據(jù)，并將當(dāng)前行為指定行 這里的n可正可負(fù)，n>0 往下翻，n<0 往上翻
FETCH RELATIVE 3 FROM C --相對(duì)于當(dāng)前行的后3行數(shù)據(jù)，并將當(dāng)前行為指定行 這里的n可正可負(fù)
FETCH RELATIVE -2 FROM C --相對(duì)于當(dāng)前行的前2行數(shù)據(jù)，并將當(dāng)前行為指定行
FETCH PRIOR FROM C ----相對(duì)于當(dāng)前行的前1行數(shù)據(jù)
FETCH FIRST FROM C --剛開始第一行的數(shù)據(jù)，并將當(dāng)前行為指定行
FETCH NEXT FROM C --相對(duì)于當(dāng)前行的后1行數(shù)據(jù)
CLOSE C
DEALLOCATE C
結(jié)果（可以參考第一個(gè)結(jié)果分析）：
具體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.
以上就是詳解SQL游標(biāo)的用法的詳細(xì)內(nèi)容，更多關(guān)于SQL游標(biāo)用法的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章！
來源：腳本之家
鏈接：https://www.jb51.net/article/188053.htm
申請(qǐng)創(chuàng)業(yè)報(bào)道，分享創(chuàng)業(yè)好點(diǎn)子。點(diǎn)擊此處，共同探討創(chuàng)業(yè)新機(jī)遇！
