请问该怎样 用”原表名+数字“组合而成的“新表名”?
我想实现的效果是,当删除某个表的记录时候,触发删除其他表中关联字段的记录,因此我写了以下触发器:
create trigger user_delete
on dbo.Tb_User
for delete
as
declare @userId int
declare @sectionCount int
declare @tmpId int
select @tmpId = 0
select @userId=Us_id from deleted
select @sectionCount=count(*) from Tb_Section
while(@tmpId<@sectionCount)
begin
delete from 'Tb_Topic_'+char(@tmpId) where Us_id=@userId
delete from 'Tb_Follow_'+char(@tmpId) where Us_id=@userId
delete from 'Tb_Reply_'+char(@tmpId) where Us_id=@userId
select @tmpId = @tmpId +1
end
但是在生成时候提示出错。
看看我以上的触发器,其实就是想用”原表名+数字“组合而成的“新表名”,然后删除对应记录,请教高人,该怎样改写?
我想实现的效果是,当删除某个表的记录时候,触发删除其他表中关联字段的记录,因此我写了以下触发器:
create trigger user_delete
on dbo.Tb_User
for delete
as
declare @userId int
declare @sectionCount int
declare @tmpId int
select @tmpId = 0
select @userId=Us_id from deleted
select @sectionCount=count(*) from Tb_Section
while(@tmpId<@sectionCount)
begin
delete from 'Tb_Topic_'+char(@tmpId) where Us_id=@userId
delete from 'Tb_Follow_'+char(@tmpId) where Us_id=@userId
delete from 'Tb_Reply_'+char(@tmpId) where Us_id=@userId
select @tmpId = @tmpId +1
end
但是在生成时候提示出错。
看看我以上的触发器,其实就是想用”原表名+数字“组合而成的“新表名”,然后删除对应记录,请教高人,该怎样改写?
on dbo.Tb_User
for delete
as
declare @userId int
declare @sectionCount int
declare @tmpId int
select @tmpId = 0
select @userId=Us_id from deleted
select @sectionCount=count(*) from Tb_Section
while(@tmpId<@sectionCount)
begin
declare @s varchar(8000)
select @s='
delete from Tb_Topic_'+ltrim(@tmpId) +' where Us_id='+ltrim(@userId)+';
delete from Tb_Follow_'+ltrim(@tmpId)+' where Us_id='+ltrim(@userId)+';
delete from Tb_Reply_'+ltrim(@tmpId)+' where Us_id='+ltrim(@userId)
exec(@s)
select @tmpId = @tmpId +1
endtry
on dbo.Tb_User
for delete
asdeclare @sectionCount int
declare @tmpId int
select @tmpId = 0select @sectionCount=count(*) from Tb_Section
while(@tmpId<@sectionCount)
begin
declare @s1 varchar(8000),@s2 varchar(8000),@s3 varchar(8000)
set @s1='delete t from Tb_Topic_'+rtrim(@tmpId)+' t join deleted d on t.Us_id=d.Us_id'
set @s2='delete t from Tb_Follow_'+rtrim(@tmpId)+' t join deleted d on t.Us_id=d.Us_id'
set @s3='delete t from Tb_Reply_'+rtrim(@tmpId)+' t join deleted d on t.Us_id=d.Us_id'
exec(@s1)
exec(@s2)
exec(@s3)
set @tmpId = @tmpId +1
endtry
1 :普通SQL语句可以用Exec执行 eg: Select * from tableName
Exec('select * from tableName')
Exec sp_executesql N'select * from tableName' -- 请注意字符串前一定要加N 2:字段名,表名,数据库名之类作为变量时,必须用动态SQL eg:
declare @fname varchar(20)
set @fname = 'FiledName'
Select @fname from tableName -- 错误,不会提示错误,但结果为固定值FiledName,并非所要。
Exec('select ' + @fname + ' from tableName') -- 请注意 加号前后的 单引号的边上加空格 当然将字符串改成变量的形式也可
declare @fname varchar(20)
set @fname = 'FiledName' --设置字段名 declare @s varchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句会报错 declare @s Nvarchar(1000) -- 注意此处改为nvarchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确 3. 输出参数
declare @num int,
@sqls nvarchar(4000)
set @sqls='select count(*) from tableName'
exec(@sqls)
--如何将exec执行结果放入变量中? declare @num int,
@sqls nvarchar(4000)
set @sqls='select @a=count(*) from tableName '
exec sp_executesql @sqls,N'@a int output',@num output
select @num
on dbo.Tb_User
for delete
as
declare @userId int
declare @sectionCount int
declare @tmpId int
select @tmpId = 0
select @sectionCount=count(*) from Tb_Section
while(@tmpId<@sectionCount)
begin
declare @s varchar(8000)
select @s='
delete a from Tb_Topic_'+ltrim(@tmpId) +' a join deleted b on a.Us_id=b.Us_id;
delete a from Tb_Follow_'+ltrim(@tmpId)+' a join deleted b on a.Us_id=b.Us_id;
delete a from Tb_Reply_'+ltrim(@tmpId)+' a join deleted b on a.Us_id=b.Us_id'
exec(@s)
select @tmpId = @tmpId +1
end7L说的合理,我只改语法部份。若考虑批删,我那个也改一下,改为单变量的。效果一样。
“delete a from Tb_Topic_'+ltrim(@tmpId) +' a join deleted b on a.Us_id=b.Us_id;“
这句怎么理解?字符b 代表哪个表?为什么要加上最后join这句喔?