游标代码举例数据库教程

游标代码举例数据库教程

游标代码举例数据库教程 篇1

游标

1.对低于当前平均价格的书，均提价50%

2对于高于或等于当前平均价格的书，均降价25%

代码如下：

declare title_update cursor

for select title_id,price from titles

for update

go

局部变量

declare @avg_price money,@title_id tid,@price money

open title_update

begin tran

计算平均书价

select @avg_price=avg(price) from titles holdlock

fetch title_update into @title_id,@price

while @@sqlstatus!=2

begin

if @@sqlstatus=1

begin

rollback tran

raiserror 21001 “Fetch failed in cursor”

close title_update

deallocate cursor title_update

return

end

if @price<@avg_price

提价50%

update titles set price = price * $1.50

where current of title_update

else

降价25%

update titles set price = price * $.75

where current of title_update

if @@error!=0

begin

rollback tran

raiserror 2 “Update failed”

close title_update

deallocate cursor title_update

return

end

fetch title_update into @title_id,@price

end

commit

close title_update

deallocate cursor title_update

go