How to create custom, dynamic string sequence in SQL Server - sql

Question

Is there any way to dynamically build sequences containing dates/strings/numbers in SQL Server?
In my application, I want every order to have a unique identificator that is a sequence of: Type of order, Year, Month, Incrementing number
(ex: NO/2016/10/001, NO/2016/10/002)
where NO = "Normal order", 2016 is a year, 10 is a month and 001 is an incrementing number. The idea is that it is easier for employees to comunicate using these types of identificators (of course this sequence would not be primary key of database table)
I know that I could create a stored procedure that would take Order type as an argument and return the sequence, but I'm curious if there is any better way to do it.
Cheers!

Answer 1

An IDENTITY column might have gaps. Just imagine an insert which is rollbacked out of any reason...
You could use ROW_NUMBER() OVER(PARTITION BY CONVERT(VARCHAR(6),OrderDate,112) ORDER BY OrderDate) in order to start a sorted numbering starting with 1 for each month. What will be best is depending on the following question: Are there parallel insert operations?
As this order name should be unique, you might run into unique-key-violations where you'd need complex mechanisms to work around...
If it is possible for you to use the existing ID you might use a scalar function together with a computed column (might be declared persistant):
CREATE TABLE OrderType(ID INT,Name VARCHAR(100),Abbr VARCHAR(2));
INSERT INTO OrderType VALUES(1,'Normal Order','NO')
,(2,'Special Order','SO');
GO
CREATE FUNCTION dbo.OrderCaption(#OrderTypeID INT,#OrderDate DATETIME,#OrderID INT)
RETURNS VARCHAR(100)
AS
BEGIN
RETURN ISNULL((SELECT Abbr FROM OrderType WHERE ID=#OrderTypeID),'#NA')
+ '/' + CAST(YEAR(#OrderDate) AS VARCHAR(4))
+ '/' + REPLACE(STR(MONTH(#OrderDate),2),' ','0')
+ '/' + REPLACE(STR(#OrderID,5),' ','0')
END
GO
CREATE TABLE YourOrder
(
ID INT IDENTITY
,OrderDate DATETIME DEFAULT(GETDATE())
,OrderTypeID INT NOT NULL --foreign key...
,Caption AS dbo.OrderCaption(OrderTypeID,OrderDate,ID)
);
GO
INSERT INTO YourOrder(OrderDate,OrderTypeID)
VALUES({ts'2016-01-01 23:23:00'},1)
,({ts'2016-02-02 12:12:00'},2)
,(GETDATE(),1);
GO
SELECT * FROM YourOrder
The result
ID OrderDate OrderTypeID Caption
1 2016-01-01 23:23:00.000 1 NO/2016/01/00001
2 2016-02-02 12:12:00.000 2 SO/2016/02/00002
3 2016-10-23 23:16:23.990 1 NO/2016/10/00003

Answer 2

You could create a computed column in your table definition which concatenates other values in your database into the kind of Identifier you're looking for.
Try this for a simplified example:-
CREATE TABLE Things (
[Type of Order] varchar(10),
[Year] int,
[Month] int,
[Inc Number] int identity(1,1),
[Identifier] as [Type of Order] + '/' + cast([Year] as varchar) + '/' + cast([Month] as varchar) + '/' + cast([Inc Number] as varchar)
)
insert into Things
values
('NO',2016,10)
select * from Things
If you wanted to do something more complex you could always use a trigger to update the column post insert or update.