scroll游标是只读的吗？

[hljhl]

我定义了如下游标
declare scroll cur_tjb cursor for select bh,tj,ws from b_glryyb1 where bh is not null for update
当运行时提示“是read only 游标不能for update”
如果去掉"scroll"就可修改。因为我要倒着走指针，所以要"cursor",而且，如果不要"scroll",加上"order by bh"也有如上提示。请教为什么？

[txlicenhe]

SQL2000的模板
-- =============================================
-- Declare and using an UPDATE cursor
-- =============================================
DECLARE <@variable_1, sysname, @v1> <datatype_for_variable_1, sysname, varchar(20)>,
<@variable_2, sysname, @v2> <datatype_for_variable_2, sysname, varchar(40)>

DECLARE <cursor_name, sysname, test_cursor> CURSOR
FOR SELECT <column_1, sysname, au_fname>, <column_2, sysname, au_lname> FROM <table_name, sysname, pubs.dbo.authors>
FOR UPDATE of <column_1, sysname, au_fname>

DECLARE @count smallint
SELECT @count = 1

OPEN <cursor_name, sysname, test_cursor>
FETCH NEXT FROM <cursor_name, sysname, test_cursor> INTO <@variable_1, sysname, @v1>, <@variable_2, sysname, @v2>

WHILE (@@fetch_status <> -1)
BEGIN
IF (@@fetch_status <> -2)
BEGIN
-- PRINT 'add user-defined code here...'
-- eg
PRINT 'updating record of ' + @v1 + ' ' + @v2
UPDATE pubs.dbo.authors
SET au_fname = @v1 + '-' + CAST(@count AS varchar(4))
WHERE au_lname = @v2
END
FETCH NEXT FROM <cursor_name, sysname, test_cursor> INTO <@variable_1, sysname, @v1>, <@variable_2, sysname, @v2>
SELECT @count = @count + 1
END

CLOSE <cursor_name, sysname, test_cursor>
DEALLOCATE <cursor_name, sysname, test_cursor>
GO

[hljhl]

谢谢！我怎么写才能满足即能可修又能向后移动游标！！