Alternatives to using Max+1 to create a user friendly unique sequence numbers

Question

I have the repository method inside my asp.net mvc web application, to automatically generate a unique sequence number called Tag:-

public void InsertOrUpdat         


        

Answer 1

A complete solution to this problem would be to combine the use of an auto incrementing column and computed column.

The table would look something like this:

CREATE TABLE [dbo].[somedata](
    [id] [bigint] IDENTITY(1,1) NOT NULL,
    [reference] [varchar](50) NULL,
    [STag]  AS ('S'+CONVERT([varchar](19),[id],(0))),
    CONSTRAINT [PK_somedata] PRIMARY KEY CLUSTERED ([id] ASC)
)   

With a mapping:

public class SomeDataMap : EntityTypeConfiguration
{
    public SomeDataMap()
    {
        // Primary Key
        this.HasKey(t => t.id);

        // Properties
        this.Property(t => t.id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        this.Property(t => t.reference)
            .HasMaxLength(50);

        this.Property(t => t.STag)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed);
    }
}