SQL Server: auto-generated custom format sequence number - sql

Question

I am working with Microsoft SQL Server 2014. In our requirement, custom formatted sequence number is include.
The sequence number format is CAT-YYYY-MM-NNNNNN. Sample data:
CAT-2016-10-000001
CAT-2016-10-000002
.
.
.
CAT-2016-10-999999
I don't want to use GUID or any other and I want to work with a procedure or function.
So, I am trying with this:
CREATE TABLE [category]
(
[id] int NOT NULL UNIQUE IDENTITY,
[category_no] nvarchar(20) NOT NULL,
[category_name] nvarchar(50) NOT NULL,
PRIMARY KEY ([id])
);
CREATE FUNCTION generate_category_no()
RETURNS CHAR(20)
AS
BEGIN
DECLARE #category_no CHAR(20)
SET #category_no = (SELECT MAX(category_no) FROM category)
IF #category_no IS NULL
SET #category_no = 'CAT-' + YEAR(getDate()) + '-' + MONTH(getDate()) + '-000001'
DECLARE #no int
SET #no = RIGHT(#category_no,6) + 1
RETURN 'CAT-' + YEAR(getDate()) + '-' + MONTH(getDate()) + '-' + right('00000' + CONVERT(VARCHAR(10),#no),6)
END
GO
ALTER TABLE category DROP COLUMN category_no;
ALTER TABLE category ADD category_no AS dbo.generate_category_no();
INSERT INTO category (category_name)
VALUES ('BMW'), ('JAGUAR');
When I run the above SQL in step-by-step, it is OK. It shown no error. But when I run the following command:
SELECT * FROM category;
it shows the following error:
Msg 217, Level 16, State 1, Line 1
Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).
I don't know how to solve this one. And even I don't know my function has worked or not. I referenced from internet for this function.
ADDED
I need to reset sequence no for every month. Eg. for next month, no should be as follow:
CAT-2016-11-000001
Please, enlighten me. Thanks in advance!

Answer 1

Modify your function as below
ALTER TABLE category DROP COLUMN category_no;
alter FUNCTION dbo.generate_category_no( #id int)
RETURNS CHAR(20)
AS
BEGIN
RETURN 'CAT-' + cast(YEAR(getDate()) as varchar(10)) + '-' + cast(MONTH(getDate()) as varchar(10))+ '-' + right('00000' + CONVERT(VARCHAR(10),#id),6)
END
ALTER TABLE category ADD category_no AS dbo.generate_category_no(id);
INSERT INTO category
(category_name)
VALUES
('BMW13'),
('JAGUAR');
SELECT * FROM category will give the below result.
1 BMW CAT-2016-10-000001
2 JAGUAR CAT-2016-10-000002
3 BMW1 CAT-2016-10-000003
4 BMW13 CAT-2016-10-000004

Answer 2

Try this:
To initialize your new field:
ALTER TABLE category DROP COLUMN category_no;
ALTER TABLE category ADD category_no CHAR(20)
UPDATE category set category_no = dbo.generate_category_no()
For other insert:
CREATE TRIGGER [dbo].[category_i]
ON [dbo].[category]
AFTER INSERT
AS BEGIN
UPDATE category
SET category_no = dbo.generate_category_no()
FROM inserted
WHERE category.pk = inserted.pk
END
But you can try to use SEQUENCE feature, available on Sql Server by 2012 version
About SEQUENCE you can see here

Answer 3

Biggest flaw in your function is it will not work for Batch Insert's
Since you have ID auto generated, here is a easier way to do this
category_no AS Concat('CAT-', Year(Getdate()), '-', Month(Getdate()), '-', RIGHT(Concat('00000', id), 6))
Demo
CREATE TABLE #seq
(
id INT IDENTITY(1, 1),
name VARCHAR(10),
category_no AS Concat('CAT-', Year(Getdate()), '-', Month(Getdate()), '-', RIGHT(Concat('00000', id), 6))
)
INSERT INTO #seq
(name)
VALUES ('val')
Result :
id name category_no
-- ---- -----------
1 val CAT-2016-10-000001

Answer 4

Finally, I solved the problem. My Function look like as follow:
CREATE FUNCTION generate_category_no()
RETURNS CHAR(20)
AS
BEGIN
DECLARE #category_no CHAR(20)
SET #category_no = (SELECT MAX(category_no) FROM category WHERE category_no LIKE CONCAT('CAT-', YEAR(getDate()), '-', MONTH(getDate()), '-%'))
IF #category_no is null SET #category_no = CONCAT('CAT-', YEAR(getDate()), '-', MONTH(getDate()), '-000000')
DECLARE #no INT
SET #no = RIGHT(#category_no,6) + 1
RETURN CONCAT('CAT-', YEAR(getDate()), '-', MONTH(getDate()), '-', RIGHT('00000' + CONVERT(VARCHAR(10),#no),6))
END
GO
And I insert data as follow:
INSERT INTO category (category_no, category_name) VALUES (dbo.generate_category_no(),'BMW');
INSERT INTO category (category_no, category_name) VALUES (dbo.generate_category_no(),'JAGUAR');
One things is that We can call function from INSERT query.
So, when I run the following sql:
SELECT * FROM category;
It give the result as shown in below.
+---+--------------------+--------------+
|id |category_no |category_name |
+---+--------------------+--------------+
| 1 |CAT-2016-10-000001 | BMW |
| 2 |CAT-2016-10-000002 | JAGUAR |
+---+--------------------+--------------+
Thanks everybody for helping me. Thanks!!!