如何在实体框架中启用身份？

Question

我正在尝试在我的代码中使用 Is Identity 来增加 TransactionId。但它显示以下错误：

SqlException：无法为标识列插入显式值 当 IDENTITY_INSERT 设置为 OFF 时，表 'TransactionHistories'。

我尝试使用[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] 语法。但它没有用。

public partial class TransactionHistories
    {
        [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
        public int TransactionId { get; set; }

        public DateTime? TransactionDate { get; set; }
        public long? CheckingAccountNumber { get; set; }
        public long? SavingAccountNumber { get; set; }
        [DisplayName("Transffered Amount")]
        public decimal? Amount { get; set; }
        public decimal? Transactionfee { get; set; }
        public long? TransactionTypeId { get; set; }
    }

---

            TransactionHistories = new TransactionHistories();
            TransactionTypes = new TransactionTypes();

            if (!ModelState.IsValid)
            {
                return Page();
            }

            SavingAccounts.Balance = SavingAccounts.Balance - Amount;
            CheckingAccounts.Balance = CheckingAccounts.Balance + Amount;

            //TransactionHistories.TransactionId = TransactionHistories.TransactionId + 1;
            TransactionHistories.TransactionDate = DateTime.Now;
            TransactionHistories.CheckingAccountNumber = CheckingAccounts.CheckingAccountNumber;
            TransactionHistories.SavingAccountNumber = SavingAccounts.SavingAccountNumber;
            TransactionHistories.Amount = Amount;
            TransactionHistories.Transactionfee = 0;
            TransactionHistories.TransactionType = "SavingToChecking";

上面是我的模型类，TransactionId 是主键，这是我尝试使用 Is Identity 使其增加 1 的值。我怎样才能使这项工作？请给我任何建议和帮助。

Answer 1

Cannot insert explicit value for identity column in table 'table' when IDENTITY_INSERT is set to OFF

SET IDENTITY_INSERT "table" 开启