A. 使用简单游标和语法 打开该游标时所生成的结果集包括 pubs 数据库的 authors 表中的所有行和列。可以更新该游标,对该游标所做的所有更新和删除均在提取中表现出来。因为没指定 SCROLL 选项,FETCH NEXT 是唯一可用的提取选项。DECLARE authors_cursor CURSOR FOR SELECT * FROM authors OPEN authors_cursor FETCH NEXT FROM authors_cursorB. 使用嵌套游标生成报表输出 下例显示如何嵌套游标以生成复杂的报表。为每个作者声明内部游标。SET NOCOUNT ONDECLARE @au_id varchar(11), @au_fname varchar(20), @au_lname varchar(40), @message varchar(80), @title varchar(80)PRINT "-------- Utah Authors report --------"DECLARE authors_cursor CURSOR FOR SELECT au_id, au_fname, au_lname FROM authors WHERE state = "UT" ORDER BY au_idOPEN authors_cursorFETCH NEXT FROM authors_cursor INTO @au_id, @au_fname, @au_lnameWHILE @@FETCH_STATUS = 0 BEGIN PRINT " " SELECT @message = "----- Books by Author: " + @au_fname + " " + @au_lname PRINT @message -- Declare an inner cursor based -- on au_id from the outer cursor. DECLARE titles_cursor CURSOR FOR SELECT t.title FROM titleauthor ta, titles t WHERE ta.title_id = t.title_id AND ta.au_id = @au_id -- Variable value from the outer cursor OPEN titles_cursor FETCH NEXT FROM titles_cursor INTO @title IF @@FETCH_STATUS <> 0 PRINT " <<No Books>>" WHILE @@FETCH_STATUS = 0 BEGIN
SELECT @message = " " + @title PRINT @message FETCH NEXT FROM titles_cursor INTO @title
END CLOSE titles_cursor DEALLOCATE titles_cursor
-- Get the next author. FETCH NEXT FROM authors_cursor INTO @au_id, @au_fname, @au_lname ENDCLOSE authors_cursor DEALLOCATE authors_cursor GO-------- Utah Authors report --------
----- Books by Author: Anne Ringer The Gourmet Microwave Is Anger the Enemy?
----- Books by Author: Albert Ringer Is Anger the Enemy? Life Without Fear 详情请见联机帮助
打开该游标时所生成的结果集包括 pubs 数据库的 authors 表中的所有行和列。可以更新该游标,对该游标所做的所有更新和删除均在提取中表现出来。因为没指定 SCROLL 选项,FETCH NEXT 是唯一可用的提取选项。DECLARE authors_cursor CURSOR
FOR SELECT * FROM authors
OPEN authors_cursor
FETCH NEXT FROM authors_cursorB. 使用嵌套游标生成报表输出
下例显示如何嵌套游标以生成复杂的报表。为每个作者声明内部游标。SET NOCOUNT ONDECLARE @au_id varchar(11), @au_fname varchar(20), @au_lname varchar(40),
@message varchar(80), @title varchar(80)PRINT "-------- Utah Authors report --------"DECLARE authors_cursor CURSOR FOR
SELECT au_id, au_fname, au_lname
FROM authors
WHERE state = "UT"
ORDER BY au_idOPEN authors_cursorFETCH NEXT FROM authors_cursor
INTO @au_id, @au_fname, @au_lnameWHILE @@FETCH_STATUS = 0
BEGIN
PRINT " "
SELECT @message = "----- Books by Author: " +
@au_fname + " " + @au_lname PRINT @message -- Declare an inner cursor based
-- on au_id from the outer cursor. DECLARE titles_cursor CURSOR FOR
SELECT t.title
FROM titleauthor ta, titles t
WHERE ta.title_id = t.title_id AND
ta.au_id = @au_id -- Variable value from the outer cursor OPEN titles_cursor
FETCH NEXT FROM titles_cursor INTO @title IF @@FETCH_STATUS <> 0
PRINT " <<No Books>>" WHILE @@FETCH_STATUS = 0
BEGIN
SELECT @message = " " + @title
PRINT @message
FETCH NEXT FROM titles_cursor INTO @title
END CLOSE titles_cursor
DEALLOCATE titles_cursor
-- Get the next author.
FETCH NEXT FROM authors_cursor
INTO @au_id, @au_fname, @au_lname
ENDCLOSE authors_cursor
DEALLOCATE authors_cursor
GO-------- Utah Authors report --------
----- Books by Author: Anne Ringer
The Gourmet Microwave
Is Anger the Enemy?
----- Books by Author: Albert Ringer
Is Anger the Enemy?
Life Without Fear
详情请见联机帮助
cursor就是一个结果集,这个结果集可以象ado记录集一样的,移动记录指针。最关键是,是一个记录指针的概念,注意,sqlserver中,普通的sql语句是没有记录指针概念的。
以前的数据库(vfp,dbase),都是基于记录的。都有记录指针的概念