SQL Server: how to generate serial number by dynamic SQL - sql-server

Question

create procedure test
(#TABLE_NAME varchar(20))
as
declare #lastval varchar(10)
set #lastval = right('000000000' + convert(varchar(10),
(select IsNull(max(Serialno), 0) + 1
from #TABLE_NAME)), 10)
return #lastval
end
Now tell me how I could compose or form dynamic SQL with above SQL where I will pass table name to store procedure when call that stored procedure?
How to return #lastval value to its calling environment?
How to call stored procedure test from another stored procedure where I will store the return value ?
Guide me with sample code.

Answer 1

Genearlly, it's best to use an IDENTITY or a SEQUENCE to assign serial numbers. A zero-padded string or other formatting requirements could be added to the table as a computed column based on the underlying serial integer or formatted in the app code. However, both IDENTITY and SEQUENCE may have gaps, such as due to rollbacks or SQL Server service restart.
In cases where an unbroken sequence of serial values is required by business, one can maintan the last assigned values in a table and assign values transactionally. Below is an example that returns the value using an OUTPUT parameter. Although the proc in your question uses the stored proc RETURN value for this purpose, that should only be used to indicate success or failure, not return data.
CREATE TABLE dbo.TableSerialNumber(
TableName sysname NOT NULL
CONSTRAINT PK_SerialNumber PRIMARY KEY
, SerialNumber int NOT NULL
, FormatString nvarchar(20) NULL
);
GO
INSERT INTO dbo.TableSerialNumber VALUES('Invoice', 0, '0000000000');
INSERT INTO dbo.TableSerialNumber VALUES('PurchaseOrder', 0, '0000000000');
GO
CREATE PROC dbo.GetNextSerialNumberForTable
#TableName sysname
, #FormattedSerialNumber varchar(10) OUTPUT
AS
SET NOCOUNT ON;
DECLARE
#SerialNumber int
, #FormatString nvarchar(20);
UPDATE dbo.TableSerialNumber
SET
#SerialNumber = SerialNumber += 1
, #FormatString = FormatString
WHERE TableName = #TableName;
IF ##ROWCOUNT = 0
RAISERROR('Table %s does not exist in dbo.TableSerialNumber', 16, 1, #TableName);
SET #FormattedSerialNumber = CAST(FORMAT(#SerialNumber, #FormatString) AS varchar(10));
GO
--example usage
CREATE PROC dbo.InsertInvoice
#InvoiceData int
AS
SET XACT_ABORT ON;
DECLARE #InvoiceNumber varchar(10);
BEGIN TRY
BEGIN TRAN;
EXECUTE dbo.GetNextSerialNumberForTable
#TableName = N'Invoice'
, #FormattedSerialNumber = #InvoiceNumber OUTPUT;
INSERT INTO dbo.Invoice (InvoiceID, InvoiceData)
VALUES(#InvoiceNumber, #InvoiceData);
SELECT #InvoiceNumber AS InvoiceNumber;
COMMIT;
END TRY
BEGIN CATCH
IF ##TRANCOUNT > 0 ROLLBACK;
THROW;
END CATCH;
GO