Question

I need to enter primary key in table as in below format

YYYY/MMM/NNNNNN

Where, YYYY is the current year, MMM is Month , and NNNNNN is a sequence no from 000001, 000002, 000003, .... 999999.

So my primary key will look like 2012/Oct/000001 or 2012/Oct/000010 ….

How can I generate this type of code..

I can get Year and Month from Getdate() function. But how can I manage sequence number on every insert. can you please give me logic for that?

Answer 1

By far the easiest way would be to let SQL Server handle the dishing out of consecutive numbers using an INT IDENTITY column – and then use a trigger to create that specific format that you need, in a separate column.

So given this table:

CREATE TABLE SampleTable 
             (ID INT IDENTITY, SaleDate DATE, ComputedPK VARCHAR(25) )

you could use a trigger like this to compute the ComputedPK from the ID (autonumber, handled by SQL Server) and the SaleDate as the date column:

CREATE TRIGGER trgSampleTableInsert
ON dbo.SampleTable FOR INSERT
AS 
    UPDATE dbo.SampleTable
    SET ComputedPK = CAST(YEAR(i.SaleDate) AS CHAR(4)) + '/' + DATENAME(MONTH, i.SaleDate) + '/' + RIGHT('000000' + CAST(i.ID AS VARCHAR(6)), 6) 
    FROM dbo.SampleTable s
    INNER JOIN INSERTED i ON s.ID = i.ID

This approach will not start at 1 for each month, however – but do you really need that? Isn’t a sequential number (even across months) good enough?

Update: of course, if you’re using SQL Server 2012 (you didn’t specify which version of SQL Server you’re using…) – you could use a SEQUENCE object to handle the consecutive numbering – and you could even reset that sequence to 1 again every start of a month ….