久久久久久久久久久久久久av,欧美成人精品一区二区男人看,午夜成人免费视频

類(lèi)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(kāi)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(hù)ID：'+@UserId+'            '+'用戶(hù)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(hù)ID：zhizhi 用戶(hù)名：鄧?guó)欀?/p>
用戶(hù)ID：yuyu 用戶(hù)名：魏雨

用戶(hù)ID：yujie 用戶(hù)名：李玉杰

用戶(hù)ID：yuanyuan 用戶(hù)名：王夢(mèng)緣

用戶(hù)ID：YOUYOU 用戶(hù)名：lisi

用戶(hù)ID：yiyiren 用戶(hù)名：任毅

用戶(hù)ID：yanbo 用戶(hù)名：王艷波

用戶(hù)ID：xuxu 用戶(hù)名：陳佳緒

用戶(hù)ID：xiangxiang 用戶(hù)名：李慶祥

用戶(hù)ID：wenwen 用戶(hù)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(kāi)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(kāi)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）：

SQL中游標(biāo)(cursor)的基本使用實(shí)例

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.