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Question

I need to create table Drivers with multiple unique index , why I'm see this message and, how I can solve this? plz help me.

Problem is I cant do update-database on migrations

Message Error is :

Column 'Phone' in table 'dbo.Drivers' is of a type that is invalid for use as a key column in an index

public class Driver
    {
        public int DriverID { get; set; }
        [Required]
        public int Code { get; set; }
        [Required]
        public string Name { get; set; }
        [Required]
        [Index("PhoneAndIdentAndDLExpAndVRNo", Order =1)]
        public string Phone { get; set; }
        public string Email { get; set; }

        [Required]
        public DateTime DOB { get; set; }
        public int Gender { get; set; }
        [Required]
        public string Address { get; set; }
        [Required]
        [Index("PhoneAndIdentAndDLExpAndVRNo", Order = 2)]
        public string Ident { get; set; }
        [Index("PhoneAndIdentAndDLExpAndVRNo", Order = 3)]
        public string DLNo { get; set; }
        [Required]
        public DateTime DLExp { get; set; }
        [Index("PhoneAndIdentAndDLExpAndVRNo", Order = 4)]
        public string VRNo { get; set; }
        [Required]
        public DateTime VRExp { get; set; }

        public string CarType { get; set; }
        public string CarColor { get; set; }
        public string CarModel { get; set; }

        public bool IsActive { get; set; }
        public bool IsOnline { get; set; }
        public string TokenID { get; set; }
        [Required]
        public string Pwd { get; set; }

    }

Image Error

Answer 1

The max length for an index column is 900 bytes. The fix is as simple as below.

 [MaxLength(20)]
 [Index("PhoneAndIdentAndDLExpAndVRNo", Order =1)]
 public string Phone { get; set; }