How to auto increment a value in a colum

Question

1.80/5 (2 votes)

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Hello i have a table called ElectricityDailyMeterReadings which has a column called MachineID..
I am trying to enter machine ID as M001, M002, M003 ..etc.. Normally i have used integer values for my primary keys and i used simple incremental methods for auto increments

example,

SQL

UPDATE mytable
  SET logins = logins + 1
  WHERE id = 12

But since this is a string i want to know how to write it.. Thank You

Posted 4-Nov-13 17:40pm

Member 10327058

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5 solutions

Solution 3

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

Posted 4-Nov-13 20:08pm

thatraja

Solution 4

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

SQL

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

for this create a trigger which looks something like this

SQL

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

I think this must solve your question

Posted 11-Nov-13 19:01pm

Rakshith Kumar

Updated 11-Nov-13 19:25pm

v3

Solution 5

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

SQL

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

now for this i create a trigger like this

SQL

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

This works fine

Posted 12-Nov-13 16:56pm

Rakshith Kumar

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VeeraAnnapureddy · Accepted Answer · 2013-11-04T17:44:00

Solution 1

SQL

declare @temp table
(
Id int identity(1,1),
Pid as case  len(Id) when 1 then 'M'+'000'+convert(varchar,ID)
when 2 then 'M'+'000'+convert(varchar,ID)
else 'M'+convert(varchar,ID)
end
)

insert into @temp default values

select * from @temp

Posted 4-Nov-13 17:44pm

VeeraAnnapureddy

Comments

Rakshith Kumar 12-Nov-13 0:17am

I dont think this will give desired result

Soumitra Mithu · Accepted Answer · 2013-11-04T17:51:00

Solution 2

lots of helpful article available in web. please check some of this
http://stackoverflow.com/questions/10991894/auto-increment-primary-key-in-sql-server-management-studio-2012[^]

[^]
http://www.w3schools.com/sql/sql_autoincrement.asp[^]

Posted 4-Nov-13 17:51pm

Soumitra Mithu