How to set starting value for an Identity primary key in Entity Framework code first?

Question

In my project I am creating the Appointments table using Entity Framework code first. When I set my integer primary key, AppointmentNo as [Key] and [Required], it creates the table with initial primary key starting with 1.

I want the appointment numbers to start at 1000. My database is SQL Server. Please help me. Thank you in advance.

[DataContract]
public class Appointment
{
    [DataMember]
    [Key]
    [Required]
    public int AppointmentNo { get; set; }

    [DataMember]
    [Required]
    public string DoctorUN { get; set; }

    [DataMember]
    [Required]
    public string PatientUN { get; set; }
}

Probably a duplicate of https://stackoverflow.com/questions/5974554/ef-code-first-how-to-set-identity-seed — Sam Arustamyan, Sep 17 '18 at 19:29

score 6 · Accepted Answer · answered Sep 17 '18 at 19:28

6

It's not possible using ef annotations,but you can execute sql in migration UP method

Sql("DBCC CHECKIDENT ('Appointment', RESEED, 1000)");

answered Sep 17 '18 at 19:28

vborutenko

4,323
5
28
48

1

I created the table from the SQL Server Management Studio and used your query there before I executed my code, that got the job done. Thanks – Charindri Perera Sep 17 '18 at 20:11

score 5 · Answer 2 · answered Sep 11 '20 at 17:37

EF Core 3.1 You can open your migration script and edit it before updating database. EF creates this line for the identity column: .Annotation("SqlServer:Identity", "1, 1"),

you can update it to anything you want:

.Annotation("SqlServer:Identity", "Your Starting Value, Your Increment Value"),

Example: If I want OrderId column on tblOrder to start from 1000 and increment by 1:

migrationBuilder.CreateTable(
    name: "tblOrder",
    schema: "dbo",
    columns: table => new
    {
        OrderID = table.Column<int>(nullable: false)
            .Annotation("SqlServer:Identity", "1000, 1"),        
        CDate = table.Column<DateTime>(nullable: false, defaultValueSql: "getdate()")
    },
.
.
.

score 5 · Answer 3 · answered May 12 '22 at 16:00

5

In entity framework you can do this:

builder.Entity<EntityName>(b =>
        {
            b.ToTable("TabelName");
            b.Property(x => x.ColumnName).ValueGeneratedOnAdd().UseIdentityColumn(1000,1);
        });

answered May 12 '22 at 16:00

Jame

131
2
7

score -2 · Answer 4 · answered Sep 17 '18 at 19:09

-2

As long as the type of the primary key property is numeric or GUID, Code First will, by convention, automatically configure the key as an identity column.

from:EF and identity columns

answered Sep 17 '18 at 19:09

user1443098

6,487
5
38
67

But is there a way to set the starting value to a specific value and increment from that point onward ? – Charindri Perera Sep 17 '18 at 19:15
not clear from the docs. easy to fix afterwards though. and a good argument against code first. (flame on!) – user1443098 Sep 17 '18 at 19:54
read the question carefully before answering – Irshu Feb 23 '21 at 08:14

How to set starting value for an Identity primary key in Entity Framework code first?

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