How to Automatically Increment Numbers in C#

How to make an auto increment number based on a year

I have figured it out myself and thank you for the down votes

public class SerialNumber
{
    private static readonly MyDbContext DbContext = new MyDbContext();

    public static string SrNo()
    {
        var sn = DbContext.PrimaryForms.ToList().Last().FormDescription;

        var array = sn.Split('/');

        if (int.Parse(array[0]) == DateTime.Today.Year)
        {
            return array[0] + "/" + (int.Parse(array[1]) + 1);
        }

        return (int.Parse(array[0]) + 1) + "/1";
    }
}

if code is not clear, ask me for explanation, thank you.

Auto Increment the number

in c#, you can do this

string s = "UK";
int counter = 0;
if (counter < 10000)
   result = s + counter++.ToString().PadLeft(4, '0');
else
   result = s + counter++.ToString();

Output: UK0000,UK0001,UK0002......

how to auto increment the number to increment by 1 after saving

int versionNumber = 1000;

public void versionIncrement()
{
    versionNumber++;
    lblOutput.Text = versionNumber.ToString();
    lblOutput.Visible = true;
}

Best practices for auto increment a number EF Core

One way would be to do the following;

1) Use integers as keys, and set ClientNumber property to be nullable.

    public class Bar
    {
        public int BarId { get; set; }
        public ICollection<Client> Clients { get; set; }
    }

    public class Client
    {
        public int ClientId { get; set; }
        public Bar Bar { get; set; }
        public int BarId { get; set; }
        public int? ClientNumber { get; set; }
    }

2) Set ClientId to identity (automatic increment) and ClientNumber to database generated (otherwise EF Core will not re-read the value from database after insert)

entity.Property(e => e.ClientId).ValueGeneratedOnAdd();
entity.Property(e => e.ClientNumber).ValueGeneratedOnAddOrUpdate();

3) Add a trigger to modify the ClientNumber after insert

    create trigger ClientNumber on Clients after insert 
    as
    begin
        set nocount on;
        update c set ClientNumber = n.RowNum from Clients c
        inner join (
            select ClientId, ROW_NUMBER() OVER(PARTITION BY BarId ORDER BY ClientId ASC) as RowNum
            from Clients
        ) n on n.ClientId = c.ClientId
    where c.ClientId in (select ClientId from inserted)
    end

Now all works automatically on insert:

            var bar1 = new Bar() { Clients = new List<Client>() };
            var bar2 = new Bar() { Clients = new List<Client>() };

            bar1.Clients.Add(new Client());
            bar1.Clients.Add(new Client());

            bar2.Clients.Add(new Client());
            bar2.Clients.Add(new Client());

            context.Bars.AddRange(new[] { bar1, bar2 });
            await context.SaveChangesAsync();

            bar1.Clients.Add(new Client());
            bar2.Clients.Add(new Client());
            bar1.Clients.Add(new Client());
            await context.SaveChangesAsync();

Will render

ClientId    BarId   ClientNumber
1   1   1
2   1   2
6   1   3
7   1   4
3   2   1
4   2   2
5   2   3

Downside is that you cannot use the unique index IX_CLIENT_NUMBER since ClientNumber will be NULL until the trigger executes.

How to auto-increment number and letter to generate a string sequence wise in c#

Looking at your code that you've provided, it seems that you're backing this with a number and just want to convert that to a more user-friendly text representation.

You could try something like this:

private static string ValueToId(int value)
{
    var parts = new List<string>();
    int numberPart = value % 10000;
    parts.Add(numberPart.ToString("0000"));
    value /= 10000;

    for (int i = 0; i < 3 || value > 0; ++i)
    {
        parts.Add(((char)(65 + (value % 26))).ToString());
        value /= 26;
    }

    return string.Join(string.Empty, parts.AsEnumerable().Reverse().ToArray());
}

It will take the first 4 characters and use them as is, and then for the remainder of the value if will convert it into characters A-Z.

So 9999 becomes AAA9999, 10000 becomes AAB0000, and 270000 becomes ABB0000.

If the number is big enough that it exceeds 3 characters, it will add more letters at the start.

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