Column names in each table must be unique. Column name 'department_Id' in table 'UserLogins' is specified more than once

Question

class UserLogin
{
    [Key]
    public int id { get; set; }

    [StringLength(50)]
    public string userName { get; set; }

    [StringLength(20)]
    public string password { get; set; }

    public virtual Modules module { get; set; }

    public virtual Company company { get; set; }

    public virtual Department department { get; set; }
}
class Department
{
    [Key]
    public int Id { get; set; }

    [Required]
    [StringLength(50)]
    public string DeptName { get; set; }

    [Required]
    [StringLength(50)]
    public string DeptGroup { get; set; }

    [Required]
    [StringLength(15)]
    public string userComputer { get; set; }

    [Required]
    public DateTime enterDate { get; set; }

    [Required]
    public virtual UserLogin createdBy { get; set; }

    public DateTime updateDate { get; set; }

    public virtual UserLogin updatedBy { get; set; }

    public virtual ICollection<UserLogin> userLogin { get; set; }

Those are 2 table configuration I used in code first approach in C# Entity framework. But After I create the migration code the folowing configuration is created

CreateTable(
            "dbo.UserLogins",
            c => new
                {
                    id = c.Int(nullable: false, identity: true),
                    userName = c.String(maxLength: 50),
                    password = c.String(maxLength: 20),
                    company_id = c.Int(),
                    Department_Id = c.Int(),
                    department_Id = c.Int(),
                    module_id = c.Int(),
                })
            .PrimaryKey(t => t.id)
            .ForeignKey("dbo.Companies", t => t.company_id)
            .ForeignKey("dbo.Departments", t => t.Department_Id)
            .ForeignKey("dbo.Departments", t => t.department_Id)
            .ForeignKey("dbo.Modules", t => t.module_id)
            .Index(t => t.company_id)
            .Index(t => t.Department_Id)
            .Index(t => t.department_Id)
            .Index(t => t.module_id);

        CreateTable(
            "dbo.Departments",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    DeptName = c.String(nullable: false, maxLength: 50),
                    DeptGroup = c.String(nullable: false, maxLength: 50),
                    userComputer = c.String(nullable: false, maxLength: 15),
                    enterDate = c.DateTime(nullable: false),
                    updateDate = c.DateTime(nullable: false),
                    createdBy_id = c.Int(nullable: false),
                    updatedBy_id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.UserLogins", t => t.createdBy_id, cascadeDelete: true)
            .ForeignKey("dbo.UserLogins", t => t.updatedBy_id, cascadeDelete: true)
            .Index(t => t.createdBy_id)
            .Index(t => t.updatedBy_id);

And The following error Message is appeared: Column names in each table must be unique. Column name 'department_Id' in table 'UserLogins' is specified more than once. Please help me to find the mistake as I am new in code first approach in c# Entity Framework?

Answer 1

userlogin表创建代码中有两个department_id删除1行Department_id = c.int（）

Answer 2

EF adds department_id for UserLogin.department and Department_Id for Department.userLogin collection. Seems like the framework couldn't understand that the entities are connected by these properties because of extra UserLogin properties in Department . So just help EF to connect them with help of InverseProperty

//[InverseProperty("department")] for C# 5 and lower
[InverseProperty(nameof(UserLogin.department))]
public virtual ICollection<UserLogin> userLogin { get; set; }

Answer 3

Use an Id that makes sense to the class and stands on its own. An ID of ID is not unique.

Use something like this for the IDs:

public int LoginID { get; set; }
public int DeptID { get; set; }

You will have less problems with the migrations that way.