需要定制，就是这样。下面有一个样本很少你想要什么。

使用SQL Server自定义自动生成的序列 [ ^ ]

Customization needed, that's it. Below one has few samples what do you want.
Custom Auto-Generated Sequences with SQL Server[^]

你可以这样做，假设表名是mytable

You can do it this way suppose the table name is mytable

create table mytable(
id varchar(6) primary key,
name varchar(30),
someint int identity(0,1)
);

为此创建一个触发器它看起来像这样

for this create a trigger which looks something like this

create trigger [dbo].[dummy]
on [dbo].[mytable]
for insert 
as
declare @id varchar(6);
declare @someint int;
select @id=id from inserted;
select @someint=someint from inserted;
if(@someint<10)
begin
update mytable
set id='M'+'00'+convert(varchar,@someint) where id=@id
end
else
if(@someint>=10 and @someint<100)
begin
update mytable
set id='M'+'0'+convert(varchar,@someint) where id=@id
end
else 
if(@someint>=100 and @someint<1000)
begin
update mytable
set id='M'+convert(varchar,@someint) where id=@id
end
else-- Since the transaction exceeds the limit so rollback the transation
rollback

我认为这必须解决你的问题uestion

I think this must solve your question

我上面讲过的解决方案很好，但我找到了一个更好的方法来处理你的问题，因为我觉得在前一种情况下执行的时间会更多。 />
如上所述，假设我有一个名为mytable的表，就像

The solution i have told above is good but i have found a better way to deal with your problem as i felt that execution time taken in the previous case will be bit more.
As mentioned above suppose i have a table named mytable which is like

create table mytable(
id varchar(6) primary key,
name varchar(30),
someint int identity(0,1)
);

现在为此我创建一个这样的触发器

now for this i create a trigger like this

create trigger [dbo].[dummy1]
on [dbo].[mytable]
for insert 
as
declare @id varchar(6);
declare @someint int;
select @id=id from inserted;
select @someint=someint from inserted;
update mytable
set id='M'+right('000'+convert(varchar,@someint),3) where id=@id

此工作正常

This works fine