8.1创建游标
语法格式：
declare 游标名 [insensitive] cursor
[local | global]
[forward_only | scroll]
[static | keyset | dynamic |fast_forward]
[read_only | scroll_locks | optimistic]
[type_warning]
for SQL语句
[for [read only | update]]
8.2读取游标中的数据信息
语法格式：
fetch [next | prior |first | last]
[absolute n |relative n]
from 游标名 [into 变量名]
注意：@@fetch_status是一个全局变量，表示返回fetch命令的状态：
|
返回值 |
意义 |
|
0 |
fetch命令被成功执行 |
|
-1 |
fetch命令失败或者行数据超过游标数据结果集的范围 |
|
-2 |
所读取的数据已经不存在 |
use db_company
declare db_cursor5 scroll cursor
for
select * from 职工 where 性别 is not null
open db_cursor5
fetch first from db_cursor5
fetch next from db_cursor5
fetch last from db_cursor5
fetch prior from db_cursor5
fetch absolute 2 from db_cursor5
fetch relative 2 from db_cursor5
close db_cursor5
deallocate db_cursor5
8.3利用游标判断并输出数据
if @@fetch_status=0
begin
declare @t varchar(10)
declare @t1 varchar(10)
declare @t2 int
fetch first from db_cursor6 into @t,@t1,@t2
select @t as 职工号,@t1 as 职工名,@t2 as 工资
end
else
begin
print ‘不存在该记录’
end
8.4利用游标修改和删除数据
use db_company
declare db_cursor7 cursor scroll
for
select * from 职工
open db_curror7
fetch first from db_cursor7
update 职工 set 工资=工资+88 where current of db_curror7
fetch absolute 4 from db_cursor7
delete from 职工 where current of db_cursor7
close db_cursor7
deallocate db_cursor7
8.5利用游标逐条显示数据库中的记录
fetch first from db_cursor8
while @@fetch_status=0
begin
fetch next from db_curror8
end
8.6在存储过程中使用游标
create procedure db_mypro
@x int
as
begin
declare mycursor scroll cursor
for
select * from 职工
open mycursor
fetch absolute @x from mycursor
close mycursor
deallocate mycursor
end
db_mypro 2
8.7查看游标属性
利用sp_cursor_list查看当前服务器的游标及其属性，语法格式：
sp_cursor_list [@cursor_return= ] cursor_variable_name output,[@cursor_scope= ] cursor_scope
利用sp_describe_cursor查看游标的全局属性，语法格式：
sp_describe_cursor [@cursor_return= ] output_cursor_variable output
{ [ , [ @cursor_source= ] N’local’
, [ @cursor_identity= ] N’local_cursor_name’ ]
| [ , [ @cursor_source= ] N’global’
, [ , [ @cursor_identity= ] N’global_cursor_name’ ]
| [ , [ @cursor_source= ] N’variable’
, [@cursor_identity= ] N’input_cursor_variable’ ]
}
8.8创建触发器
触发器是一种特殊类型的存储过程，主要通过事件触发而被执行。
事后触发器
create trigger 触发器名 on 表名 [with encryption] for insert[,update,delete] as
begin
命令行或程序块
end
替代触发器
create trigger 触发器名 on 表名或视图名 instead of insert [, update,delete] as
begin
命令行或程序块
end
注意：触发器只能关联表或视图。为了保护代码触发器的代码内容，可以利用with encryption加密触发器中的代码内容。after只能定义在表中，不能到视图上。而instead of可以定义在视图上。
create trigger db_trigger4 on 仓库 for update
as
begin
declare @old char(10)
declare @new char(10)
select @new=仓库号 from inserted
select @old=仓库号 from deleted
update 职工set 仓库号[email protected] where 仓库号[email protected]
end
8.9修改、删除和查看触发器
8.9.1修改触发器
把create改成alter即可。
8.9.2查看触发器基本信息
execute sp_help db_trigger1 select * from sys.triggers (查看所有)
8.9.3查看触发器所使用数据对象信息
execute sp_depends db_trigger1
8.9.4查看触发器功能代码
execute sp_helptext db_trigger1
8.9.5删除触发器
drop trigger {triggername}[,n]
triggername表示要删除的触发器名，n表示可以同时删除多个触发器。