How to get next value of SQL Server sequence in Entity Framework?

You can create a simple stored procedure in SQL Server that selects the next sequence value like this:

CREATE PROCEDURE dbo.GetNextSequenceValue 
AS 
BEGIN
    SELECT NEXT VALUE FOR dbo.TestSequence;
END

and then you can import that stored procedure into your EDMX model in Entity Framework, and call that stored procedure and fetch the sequence value like this:

// get your EF context
using (YourEfContext ctx = new YourEfContext())
{
    // call the stored procedure function import   
    var results = ctx.GetNextSequenceValue();

    // from the results, get the first/single value
    int? nextSequenceValue = results.Single();

    // display the value, or use it whichever way you need it
    Console.WriteLine("Next sequence value is: {0}", nextSequenceValue.Value);
}

Update: actually, you can skip the stored procedure and just run this raw SQL query from your EF context:

public partial class YourEfContext : DbContext 
{
    .... (other EF stuff) ......

    // get your EF context
    public int GetNextSequenceValue()
    {
        var rawQuery = Database.SqlQuery<int>("SELECT NEXT VALUE FOR dbo.TestSequence;");
        var task = rawQuery.SingleAsync();
        int nextVal = task.Result;

        return nextVal;
    }
}

Since I am using Code First and I do not want to have some additional DDL, this is my way: (EF Core 2.1, SQL Server)

Define the sequence:

protected override void OnModelCreating( ModelBuilder modelBuilder )
{
    modelBuilder.HasSequence("MySequence");
}

And to retrieve it I add the following function to the context:

public int GetMySequence()
{
   SqlParameter result = new SqlParameter("@result", System.Data.SqlDbType.Int)
   {
      Direction = System.Data.ParameterDirection.Output
   };

   Database.ExecuteSqlCommand(
              "SELECT @result = (NEXT VALUE FOR MySequence)", result);

   return (int)result.Value;
}

In case anyone else who is working with Entity Framework Core ends up looking here, this worked for me:

var connection = dbContext.Database.GetDbConnection();
connection.Open();
using (var cmd = connection.CreateCommand())
{
    cmd.CommandText = "SELECT NEXT VALUE FOR ACH.FileIDModifier;";
    var obj = cmd.ExecuteScalar();
    int anInt = (int)obj;
}

EF 3.1: Adding below function in DbContext. refer using Microsoft.Data.SqlClient;

 public async Task<int> NextValueForSequence(SequenceEnum.Sequence sequence)
    {
        SqlParameter result = new SqlParameter("@result", System.Data.SqlDbType.Int)
        {
            Direction = System.Data.ParameterDirection.Output
        };

        var sequenceIdentifier = sequence.GetType().GetMember(sequence.ToString()).First().GetCustomAttribute<DescriptionAttribute>().Description;

        await Database.ExecuteSqlRawAsync($"SELECT @result = (NEXT VALUE FOR [{sequenceIdentifier}])", result);

        return (int)result.Value;
    }



public class SequenceEnum
{
    public enum Sequence
    {
        [Description("Generate_First_Sequence")]
        FirstSequence,
        [Description("Generate_Second_Sequence")]
        SecondSequence,
    }
}

While calling context

await context.NextValueForSequence(SequenceEnum.Sequence.FirstSequence);

Hope this helps :)

Since this functionality doesn't come out of the box, I came up to write an extension-class for the DbContext that does the job. Have a look at this chunk of code:

public enum Sequence
{
    [Description("sequence__name__goes__here")]
    ClientNr,
    [Description("another__sequence__name")]
    OrderNr,
}
public static class MyDbContextExtensions
{
    public static int NextValueForSequence(this MyDbContext pCtx, Sequence pSequence)
    {
        SqlParameter result = new SqlParameter("@result", System.Data.SqlDbType.Int)
        {
            Direction = System.Data.ParameterDirection.Output
        };
        var sequenceIdentifier = pSequence.GetType()
                    .GetMember(pSequence.ToString())
                    .First()
                    .GetCustomAttribute<DescriptionAttribute>()
                    .Description;
        pCtx.Database.ExecuteSqlCommand($"SELECT @result = (NEXT VALUE FOR [{sequenceIdentifier}]);", result);
        return (int)result.Value;
    }
}

While I must admit that all that stuff with reflection and annotations for some might seem like an overkill, I still kinda like it.

It allows me to retrieve the value in a pretty elegant way

ctx.NextValueForSequence(Sequence.OrderNr);

It also mocks a "type proof" way, constraining me to explicitly define the different sequence names in a centralized location rather than just passing magic strings from anywhere I want.

If you don't want it that way, just change the method in order to pass the sequence name as a string. It would work just as fine.