举例：declare cursor_insert cursor for select c# from cs
declare
@i int
open cursor_insert
fetch cursor_insert into @i
while @@fetch_status=0
begin
print @i
fetch cursor_insert into @i
end
close cursor_insert
deallocate cursor_insert
declare
@i int
open cursor_insert
fetch cursor_insert into @i
while @@fetch_status=0
begin
print @i
fetch cursor_insert into @i
end
close cursor_insert
deallocate cursor_insert
是提取当前的记录值到@xx中while @@FETCH_STATUS = 0
是判断提取是否成功
fetch next from xxx into @xx--这句话是一定要加的么？
while @@FETCH_STATUS = 0
begin
...
end
fetch next from xxx <<=======这里你写错了，这句应该在while里面,要不然你是死循环
end
close xxx
deallocate xxx
select column_id from t_table
IF @@error <> 0
GOTO Closing_CursorOPEN item_group
FETCH column_id INTO @ls_id
WHILE (@@FETCH_STATUS = 0)
BEGIN
//此处处理
FETCH FETCH column_id INTO @ls_id
END
CLOSE item_group
DEALLOCATE item_group
那就是说循环写的基本是对的？每次都要加 fetch next from xxx into xx
那写fetch first from xxx into xx 和fetch last from xxx into xx
是不是一样啊？那非空那个呢？除了 fetch next from xxx放while里面
那样判断非空对不对？
A. 在简单的游标中使用 FETCH
下例为 authors 表中姓以字母 B 开头的行声明了一个简单的游标，并使用 FETCH NEXT 逐个提取这些行。FETCH 语句以单行结果集形式返回由 DECLARE CURSOR 指定的列的值。USE pubs
GO
DECLARE authors_cursor CURSOR FOR
SELECT au_lname FROM authors
WHERE au_lname LIKE "B%"
ORDER BY au_lnameOPEN authors_cursor-- Perform the first fetch.
FETCH NEXT FROM authors_cursor-- Check @@FETCH_STATUS to see if there are any more rows to fetch.
WHILE @@FETCH_STATUS = 0
BEGIN
-- This is executed as long as the previous fetch succeeds.
FETCH NEXT FROM authors_cursor
ENDCLOSE authors_cursor
DEALLOCATE authors_cursor
GOau_lname
----------------------------------------
Bennet
au_lname
----------------------------------------
Blotchet-Halls
au_lname
----------------------------------------B. 使用 FETCH 将值存入变量
下例与上例相似，但 FETCH 语句的输出存储于局部变量而不是直接返回给客户端。PRINT 语句将变量组合成单一字符串并将其返回到客户端。USE pubs
GO-- Declare the variables to store the values returned by FETCH.
DECLARE @au_lname varchar(40), @au_fname varchar(20)
DECLARE authors_cursor CURSOR FOR
SELECT au_lname, au_fname FROM authors
WHERE au_lname LIKE "B%"
ORDER BY au_lname, au_fnameOPEN authors_cursor-- Perform the first fetch and store the values in variables.
-- Note: The variables are in the same order as the columns
-- in the SELECT statement. FETCH NEXT FROM authors_cursor
INTO @au_lname, @au_fname-- Check @@FETCH_STATUS to see if there are any more rows to fetch.
WHILE @@FETCH_STATUS = 0
BEGIN -- Concatenate and display the current values in the variables.
PRINT "Author: " + @au_fname + " " + @au_lname -- This is executed as long as the previous fetch succeeds.
FETCH NEXT FROM authors_cursor
INTO @au_lname, @au_fname
ENDCLOSE authors_cursor
DEALLOCATE authors_cursor
GOAuthor: Abraham Bennet
Author: Reginald Blotchet-HallsC. 声明 SCROLL 游标并使用其它 FETCH 选项
下例创建一个 SCROLL 游标，使其通过 LAST、PRIOR、RELATIVE 和 ABSOLUTE 选项支持所有滚动能力。USE pubs
GO-- Execute the SELECT statement alone to show the
-- full result set that is used by the cursor.
SELECT au_lname, au_fname FROM authors
ORDER BY au_lname, au_fname-- Declare the cursor.
DECLARE authors_cursor SCROLL CURSOR FOR
SELECT au_lname, au_fname FROM authors
ORDER BY au_lname, au_fnameOPEN authors_cursor-- Fetch the last row in the cursor.
FETCH LAST FROM authors_cursor-- Fetch the row immediately prior to the current row in the cursor.
FETCH PRIOR FROM authors_cursor-- Fetch the second row in the cursor.
FETCH ABSOLUTE 2 FROM authors_cursor-- Fetch the row that is three rows after the current row.
FETCH RELATIVE 3 FROM authors_cursor-- Fetch the row that is two rows prior to the current row.
FETCH RELATIVE -2 FROM authors_cursorCLOSE authors_cursor
DEALLOCATE authors_cursor
GOau_lname au_fname
---------------------------------------- --------------------
Bennet Abraham
Blotchet-Halls Reginald
Carson Cheryl
DeFrance Michel
del Castillo Innes
Dull Ann
Green Marjorie
Greene Morningstar
Gringlesby Burt
Hunter Sheryl
Karsen Livia
Locksley Charlene
MacFeather Stearns
McBadden Heather
O'Leary Michael
Panteley Sylvia
Ringer Albert
Ringer Anne
Smith Meander
Straight Dean
Stringer Dirk
White Johnson
Yokomoto Akiko au_lname au_fname
---------------------------------------- --------------------
Yokomoto Akiko
au_lname au_fname
---------------------------------------- --------------------
White Johnson
au_lname au_fname
---------------------------------------- --------------------
Blotchet-Halls Reginald
au_lname au_fname
---------------------------------------- --------------------
del Castillo Innes
au_lname au_fname
---------------------------------------- --------------------
Carson Cheryl
返回被 FETCH 语句执行的最后游标的状态，而不是任何当前被连接打开的游标的状态。返回值 描述
0 FETCH 语句成功。
-1 FETCH 语句失败或此行不在结果集中。
-2 被提取的行不存在。
asDeclare @personid as varchar(50)Declare personid_cursor2 cursor for select personid from f_person
open personid_cursor2fetch next from personid_cursor2 into @personidwhile @@fetch_status=0
begin
declare @name varchar(50)
select @name=name from f_person where personid=@personid
update f_follow set personid=@name where personid=@personid fetch next from personid_cursor2 into @personid
endclose personid_cursor2
GO